Zoom lens and electronic imaging device having the same

ABSTRACT

A zoom lens includes a most object-side lens unit remaining fixed on the optical axis when the magnification of the zoom lens is changed and a focusing operation is performed; a most image-side lens unit remaining fixed when the focusing operation is performed; and a plurality of moving lens units lying between the most object-side lens unit and the most image-side lens unit, moved along the optical axis when the magnification is changed. The most object-side lens unit includes, in order from the object side, a negative lens component, a reflective optical component having a reflecting surface for bending the optical path, and a positive lens component. The most image-side lens unit has at least one aspherical surface. An electronic imaging device includes an electronic image sensor located on the image side of the zoom lens.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.11/374,010 filed on Mar. 14, 2006, now U.S. Pat. No. 7,215,486, which isa continuation of U.S. patent application Ser. No. 10/429,043 filed onMay 5, 2003, now U.S. Pat. No. 7,085,070, which claims priority toJapanese Application Nos. 2002-138835 filed on May 14, 2002 and2002-141234 filed on May 16, 2002, each of which is expresslyincorporated herein in its entirety by reference thereto.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a zoom lens and an electronic imagingdevice having this zoom lens, and in particular, to a zoom lens whichallows a slim design of a video camera, a digital camera, or any otherelectronic imaging device.

2. Description of Related Art

Recently, as the next generation camera of an alternative to a silverhalide 35 mm film (135 format) camera, special attention has beendevoted to a digital camera (an electronic camera). Such digital camerashave come to have many categories in a wide range from a high-functiontype for business use to a popular portable type.

The thickness of an optical system, notably a zoom lens system, from themost object-side surface to an imaging plane constitutes a chiefobstacle to a reduction in depth of a camera.

The slim design technique of a camera body chiefly used in recent yearsadopts a so-called collapsible lens barrel that although the opticalsystem protrudes from the front side of the camera body in photography,it is incorporated in the camera body when the camera is not used.

Examples of optical systems having possibilities that the collapsiblelens barrel is used and the slim design can be effectively achieved areset forth in Japanese Patent Kokai Nos. Hei 11-194274, Hei 11-287953,and 2000-9997. Each of the optical systems includes, in order form theobject side, a first lens unit with negative refracting power and asecond lens unit with positive refracting power so that when themagnification of the optical system is changed, both the first lens unitand the second lens unit are moved.

The adoption of the collapsible lens barrel, however, requires much timeto bring lenses into a working state from an incorporating state, whichis unfavorable for use. Furthermore, the design that the mostobject-side lens unit is moved is unfavorable for water and dust proof.Also, there is physical restriction of fabrication limit size as to thedirection of thickness of a lens part. The length of the collapsiblelens barrel is governed by the thicknesses of lens parts, and thus eventhough further compactness of an image sensor is achieved in the future,the slim design of the camera in its depth according to the compactnesscannot be expected.

On the other hand, in order to obtain a camera which does not haverising time (lens shifting time) required to bring the camera into theworking state like the collapsible lens barrel, is favorable for waterand dust proof, and is extremely small in depth, it is conceivable thatthe optical system is constructed so that the optical path (opticalaxis) is bent by a reflective optical component such as a mirror. Inthis case, even though the depth can be made small, the overall lengthof the optical path after being bent is increased, and hence dimensionsother than that of the depth tend to become large. In this constructionthat the optical path is bent, however, it can be expected that whenfurther compactness of the image sensor is realized in the future, thedepth can be made small in accordance with the compactness. On the otherhand, however, account must be taken of the influence of diffraction dueto the compactness of the image sensor.

SUMMARY OF THE INVENTION

The zoom lens according to the present invention includes, at least, amost object-side lens unit located at a most object-side position,remaining fixed on the optical axis when the magnification of the zoomlens is changed and a focusing operation is performed; a most image-sidelens unit located at a most image-side position, remaining fixed on theoptical axis when the focusing operation is performed; and moving lensunits lying between the most object-side lens unit and the mostimage-side lens unit, moved along the optical axis when themagnification is changed. The most object-side lens unit includes, inorder from the object side, a negative lens component, a front surfacemirror having a reflecting surface for bending the optical path, and apositive lens component. The most image-side lens unit has at least oneaspherical surface.

The zoom lens according to the present invention has, in order from theobject side, a first lens unit including a positive lens component,constructed as a most object-side lens unit remaining fixed when themagnification is changed; a second lens unit with negative refractingpower, constructed as a first moving lens unit moved along the opticalaxis when the magnification is changed; a third lens unit with positiverefracting power, constructed as a second moving lens unit moved alongthe optical axis when the magnification is changed; and a mostimage-side lens unit located at a most image-side position. The firstlens unit includes a negative lens component and a front surface mirrorhaving a reflecting surface for bending the optical path, arranged inthis order from the object side, and the reflecting surface isdeformable. According to the present invention, when the magnificationis changed, extending from the wide-angle position to the telephotoposition, in focusing of an infinite object point, the second lens unitis constructed so that it is moved back and forth along the optical axison the image side, following a convex path.

According to the present invention, the profile of the reflectingsurface is changed and thereby the focusing operation is performed.

According to the present invention, the reflecting surface isconstructed with a thin film with which a metal or dielectric is coated,and the thin film is connected to a power source through a plurality ofelectrodes and variable resistors. An arithmetical unit controlling theresistance values of the variable resistors is provided to control thedistribution of electrostatic forces applied to the thin film. Whereby,the profile of the reflecting surface can be changed.

The zoom lens according to the present invention includes, in order fromthe object side, a first lens unit having a reflective optical componentwith a reflecting surface for bending the optical path, constructed as amost object-side lens unit remaining fixed when the magnification ischanged; a second lens unit with negative refracting power, constructedas a first moving lens unit moved along the optical axis when themagnification is changed; a third lens unit with positive refractingpower, constructed as a second moving lens unit moved along the opticalaxis when the magnification is changed; and a most image-side lens unitlocated at a most image-side position. In this case, when themagnification is changed, extending from the wide-angle position to thetelephoto position, in focusing of the infinite object point, the secondlens unit is constructed so that it is moved back and forth along theoptical axis on the image side, following a convex path.

According to the present invention, in the focusing operation of ashort-distance object point, the second lens unit is shifted to theobject side.

According to the present invention, a lens unit moved along the opticalaxis in the focusing operation of the short-distance object point isinterposed between the third lens unit and the most image-side lensunit.

According to the present invention, the third lens unit includes acemented lens component with a positive lens and a negative lens, and asingle lens component. It is moved toward only the object side when themagnification is changed, extending from the wide-angle position to thetelephoto position.

The electronic imaging device according to the present invention has anyzoom lens mentioned above and an electronic image sensor placed on theimage side thereof.

These and other objects as well as the features and advantages of thepresent invention will become apparent from the following detaileddescription of the preferred embodiments when taken in conjunction withthe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view showing an optical arrangement, developedalong the optical axis, at the wide-angle position where the opticalpath is bent in focusing of the infinite object point, in a firstembodiment of the zoom lens according to the present invention;

FIGS. 2A, 2B, and 2C are sectional views showing optical arrangements,developed along the optical axis, at wide-angle, middle, and telephotopositions, respectively, in focusing of the infinite object point, ofthe zoom lens in the first embodiment;

FIGS. 3A, 3B, 3C, and 3D are diagrams showing aberration characteristicsat the wide-angle position, in focusing of the infinite object point, ofthe zoom lens in the first embodiment;

FIGS. 4A, 4B, 4C, and 4D are diagrams showing aberration characteristicsat the middle position, in focusing of the infinite object point, of thezoom lens in the first embodiment;

FIGS. 5A, 5B, 5C, and 5D are diagrams showing aberration characteristicsat the telephoto position, in focusing of the infinite object point, ofthe zoom lens in the first embodiment;

FIG. 6 is a sectional view showing an optical arrangement, developedalong the optical axis, at the wide-angle position where the opticalpath is bent in focusing of the infinite object point, in a secondembodiment of the zoom lens according to the present invention;

FIGS. 7A, 7B, and 7C are sectional views showing optical arrangements,developed along the optical axis, at wide-angle, middle, and telephotopositions, respectively, in focusing of the infinite object point, ofthe zoom lens in the second embodiment;

FIG. 8 is a sectional view showing an optical arrangement, developedalong the optical axis, at the wide-angle position where the opticalpath is bent in focusing of the infinite object point, in a thirdembodiment of the zoom lens according to the present invention;

FIGS. 9A, 9B, and 9C are sectional views showing optical arrangements,developed along the optical axis, at wide-angle, middle, and telephotopositions, respectively, in focusing of the infinite object point, ofthe zoom lens in the third embodiment;

FIGS. 10A, 10B, 10C, and 10D are diagrams showing aberrationcharacteristics at the wide-angle position, in focusing of the infiniteobject point, of the zoom lens in the third embodiment;

FIGS. 11A, 11B, 11C, and 11D are diagrams showing aberrationcharacteristics at the middle position, in focusing of the infiniteobject point, of the zoom lens in the third embodiment;

FIGS. 12A, 12B, 12C, and 12D are diagrams showing aberrationcharacteristics at the telephoto position, in focusing of the infiniteobject point, of the zoom lens in the third embodiment;

FIG. 13 is a sectional view showing an optical arrangement, developedalong the optical axis, at the wide-angle position where the opticalpath is bent in focusing of the infinite object point, in a fourthembodiment of the zoom lens according to the present invention;

FIGS. 14A, 14B, and 14C are sectional views showing opticalarrangements, developed along the optical axis, at wide-angle, middle,and telephoto positions, respectively, in focusing of the infiniteobject point, of the zoom lens in the fourth embodiment;

FIGS. 15A, 15B, 15C, and 15D are diagrams showing aberrationcharacteristics at the wide-angle position, in focusing of the infiniteobject point, of the zoom lens in the fourth embodiment;

FIGS. 16A, 16B, 16C, and 16D are diagrams showing aberrationcharacteristics at the middle position, in focusing of the infiniteobject point, of the zoom lens in the fourth embodiment;

FIGS. 17A, 17B, 17C, and 17D are diagrams showing aberrationcharacteristics at the telephoto position, in focusing of the infiniteobject point, of the zoom lens in the fourth embodiment;

FIG. 18 is a sectional view showing an optical arrangement, developedalong the optical axis, at the wide-angle position where the opticalpath is bent in focusing of the infinite object point, in a fifthembodiment of the zoom lens according to the present invention;

FIGS. 19A, 19B, and 19C are sectional views showing opticalarrangements, developed along the optical axis, at wide-angle, middle,and telephoto positions, respectively, in focusing of the infiniteobject point, of the zoom lens in the fifth embodiment;

FIG. 20 is a sectional view showing an optical arrangement, developedalong the optical axis, at the wide-angle position where the opticalpath is bent in focusing of the infinite object point, in a sixthembodiment of the zoom lens according to the present invention;

FIGS. 21A, 21B, and 21C are sectional views showing opticalarrangements, developed along the optical axis, at wide-angle, middle,and telephoto positions, respectively, in focusing of the infiniteobject point, of the zoom lens in the sixth embodiment;

FIG. 22 is a sectional view showing an optical arrangement, developedalong the optical axis, at the wide-angle position where the opticalpath is bent in focusing of the infinite object point, in a seventhembodiment of the zoom lens according to the present invention;

FIGS. 23A, 23B, and 23C are sectional views showing opticalarrangements, developed along the optical axis, at wide-angle, middle,and telephoto positions, respectively, in focusing of the infiniteobject point, of the zoom lens in the seventh embodiment;

FIG. 24 is a sectional view showing an optical arrangement, developedalong the optical axis, at the wide-angle position where the opticalpath is bent in focusing of the infinite object point, in an eighthembodiment of the zoom lens according to the present invention;

FIGS. 25A, 25B, and 25C are sectional views showing opticalarrangements, developed along the optical axis, at wide-angle, middle,and telephoto positions, respectively, in focusing of the infiniteobject point, of the zoom lens in the eighth embodiment;

FIGS. 26A, 26B, 26C, and 26D are diagrams showing aberrationcharacteristics at the wide-angle position, in focusing of the infiniteobject point, of the zoom lens in the eighth embodiment;

FIGS. 27A, 27B, 27C, and 27D are diagrams showing aberrationcharacteristics at the middle position, in focusing of the infiniteobject point, of the zoom lens in the eighth embodiment;

FIGS. 28A, 28B, 28C, and 28D are diagrams showing aberrationcharacteristics at the telephoto position, in focusing of the infiniteobject point, of the zoom lens in the eighth embodiment;

FIGS. 29A, 29B, 29C, and 29D are diagrams showing aberrationcharacteristics at the wide-angle position, in focusing of theshort-distance object point, of the zoom lens in the eighth embodiment;

FIGS. 30A, 30B, 30C, and 30D are diagrams showing aberrationcharacteristics at the middle position, in focusing of theshort-distance object point, of the zoom lens in the eighth embodiment;

FIGS. 31A, 31B, 31C, and 31D are diagrams showing aberrationcharacteristics at the telephoto position, in focusing of theshort-distance object point, of the zoom lens in the eighth embodiment;

FIG. 32 is a sectional view showing an optical arrangement, developedalong the optical axis, at the wide-angle position where the opticalpath is bent in focusing of the infinite object point, in a ninthembodiment of the zoom lens according to the present invention;

FIGS. 33A, 33B, and 33C are sectional views showing opticalarrangements, developed along the optical axis, at wide-angle, middle,and telephoto positions, respectively, in focusing of the infiniteobject point, of the zoom lens in the ninth embodiment;

FIGS. 34A, 34B, 34C, and 34D are diagrams showing aberrationcharacteristics at the wide-angle position, in focusing of the infiniteobject point, of the zoom lens in the ninth embodiment;

FIGS. 35A, 35B, 35C, and 35D are diagrams showing aberrationcharacteristics at the middle position, in focusing of the infiniteobject point, of the zoom lens in the ninth embodiment;

FIGS. 36A, 36B, 36C, and 36D are diagrams showing aberrationcharacteristics at the telephoto position, in focusing of the infiniteobject point, of the zoom lens in the ninth embodiment;

FIGS. 37A, 37B, 37C, and 37D are diagrams showing aberrationcharacteristics at the wide-angle position, in focusing of theshort-distance object point, of the zoom lens in the ninth embodiment;FIGS. 38A, 38B, 38C, and 38D are diagrams showing aberrationcharacteristics at the middle position, in focusing of theshort-distance object point, of the zoom lens in the ninth embodiment;

FIGS. 39A, 39B, 39C, and 39D are diagrams showing aberrationcharacteristics at the telephoto position, in focusing of theshort-distance object point, of the zoom lens in the ninth embodiment;

FIG. 40 is a sectional view showing an optical arrangement, developedalong the optical axis, at the wide-angle position where the opticalpath is bent in focusing of the infinite object point, in a tenthembodiment of the zoom lens according to the present invention;

FIGS. 41A, 41B, and 41C are sectional views showing opticalarrangements, developed along the optical axis, at wide-angle, middle,and telephoto positions, respectively, in focusing of the infiniteobject point, of the zoom lens in the tenth embodiment;

FIG. 42 is a sectional view showing an optical arrangement, developedalong the optical axis, at the wide-angle position where the opticalpath is bent in focusing of the infinite object point, in an eleventhembodiment of the zoom lens according to the present invention;

FIGS. 43A, 43B, and 43C are sectional views showing opticalarrangements, developed along the optical axis, at wide-angle, middle,and telephoto positions, respectively, in focusing of the infiniteobject point, of the zoom lens in the eleventh embodiment;

FIGS. 44A, 44B, 44C, and 44D are diagrams showing aberrationcharacteristics at the wide-angle position, in focusing of the infiniteobject point, of the zoom lens in the eleventh embodiment;

FIGS. 45A, 45B, 45C, and 45D are diagrams showing aberrationcharacteristics at the middle position, in focusing of the infiniteobject point, of the zoom lens in the eleventh embodiment;

FIGS. 46A, 46B, 46C, and 46D are diagrams showing aberrationcharacteristics at the telephoto position, in focusing of the infiniteobject point, of the zoom lens in the eleventh embodiment;

FIGS. 47A, 47B, 47C, and 47D are diagrams showing aberrationcharacteristics at the wide-angle position, in focusing of theshort-distance object point, of the zoom lens in the eleventhembodiment;

FIGS. 48A, 48B, 48C, and 48D are diagrams showing aberrationcharacteristics at the middle position, in focusing of theshort-distance object point, of the zoom lens in the eleventhembodiment;

FIGS. 49A, 49B, 49C, and 49D are diagrams showing aberrationcharacteristics at the telephoto position, in focusing of theshort-distance object point, of the zoom lens in the eleventhembodiment;

FIG. 50 is a sectional view showing an optical arrangement, developedalong the optical axis, at the wide-angle position where the opticalpath is bent in focusing of the infinite object point, in a twelfthembodiment of the zoom lens according to the present invention;

FIGS. 51A, 51B, and 51C are sectional views showing opticalarrangements, developed along the optical axis, at wide-angle, middle,and telephoto positions, respectively, in focusing of the infiniteobject point, of the zoom lens in the twelfth embodiment;

FIGS. 52A, 52B, 52C, and 52D are diagrams showing aberrationcharacteristics at the wide-angle position, in focusing of the infiniteobject point, of the zoom lens in the twelfth embodiment;

FIGS. 53A, 53B, 53C, and 53D are diagrams showing aberrationcharacteristics at the middle position, in focusing of the infiniteobject point, of the zoom lens in the twelfth embodiment;

FIGS. 54A, 54B, 54C, and 54D are diagrams showing aberrationcharacteristics at the telephoto position, in focusing of the infiniteobject point, of the zoom lens in the twelfth embodiment;

FIGS. 55A, 55B, 55C, and 55D are diagrams showing aberrationcharacteristics at the wide-angle position, in focusing of theshort-distance object point, of the zoom lens in the twelfth embodiment;

FIGS. 56A, 56B, 56C, and 56D are diagrams showing aberrationcharacteristics at the middle position, in focusing of theshort-distance object point, of the zoom lens in the twelfth embodiment;

FIGS. 57A, 57B, 57C, and 57D are diagrams showing aberrationcharacteristics at the telephoto position, in focusing of theshort-distance object point, of the zoom lens in the twelfth embodiment;

FIG. 58 is a sectional view showing an optical arrangement, developedalong the optical axis, at the wide-angle position where the opticalpath is bent in focusing of the infinite object point, in a thirteenthembodiment of the zoom lens according to the present invention;

FIGS. 59A, 59B, and 59C are sectional views showing opticalarrangements, developed along the optical axis, at wide-angle, middle,and telephoto positions, respectively, in focusing of the infiniteobject point, of the zoom lens in the thirteenth embodiment;

FIGS. 60A, 60B, 60C, and 60D are diagrams showing aberrationcharacteristics at the wide-angle position, in focusing of the infiniteobject point, of the zoom lens in the thirteenth embodiment;

FIGS. 61A, 61B, 61C, and 61D are diagrams showing aberrationcharacteristics at the middle position, in focusing of the infiniteobject point, of the zoom lens in the thirteenth embodiment;

FIGS. 62A, 62B, 62C, and 62D are diagrams showing aberrationcharacteristics at the telephoto position, in focusing of the infiniteobject point, of the zoom lens in the thirteenth embodiment;

FIGS. 63A, 63B, 63C, and 63D are diagrams showing aberrationcharacteristics at the wide-angle position, in focusing of theshort-distance object point, of the zoom lens in the thirteenthembodiment;

FIGS. 64A, 64B, 64C, and 64D are diagrams showing aberrationcharacteristics at the middle position, in focusing of theshort-distance object point, of the zoom lens in the thirteenthembodiment;

FIGS. 65A, 65B, 65C, and 65D are diagrams showing aberrationcharacteristics at the telephoto position, in focusing of theshort-distance object point, of the zoom lens in the thirteenthembodiment;

FIG. 66 is a sectional view showing an optical arrangement, developedalong the optical axis, at the wide-angle position where the opticalpath is bent in focusing of the infinite object point, in a fourteenthembodiment of the zoom lens according to the present invention;

FIGS. 67A, 67B, and 67C are sectional views showing opticalarrangements, developed along the optical axis, at wide-angle, middle,and telephoto positions, respectively, in focusing of the infiniteobject point, of the zoom lens in the fourteenth embodiment;

FIG. 68 is a sectional view showing an optical arrangement, developedalong the optical axis, at the wide-angle position where the opticalpath is bent in focusing of the infinite object point, in a fifteenthembodiment of the zoom lens according to the present invention;

FIGS. 69A, 69B, and 69C are sectional views showing opticalarrangements, developed along the optical axis, at wide-angle, middle,and telephoto positions, respectively, in focusing of the infiniteobject point, of the zoom lens in the fifteenth embodiment;

FIG. 70 is a sectional view showing an optical arrangement, developedalong the optical axis, at the wide-angle position where the opticalpath is bent in focusing of the infinite object point, in a sixteenthembodiment of the zoom lens according to the present invention;

FIGS. 71A, 71B, and 71C are sectional views showing opticalarrangements, developed along the optical axis, at wide-angle, middle,and telephoto positions, respectively, in focusing of the infiniteobject point, of the zoom lens in the sixteenth embodiment;

FIGS. 72A, 72B, 72C, and 72D are diagrams showing aberrationcharacteristics at the wide-angle position, in focusing of the infiniteobject point, of the zoom lens in the sixteenth embodiment;

FIGS. 73A, 73B, 73C, and 73D are diagrams showing aberrationcharacteristics at the middle position, in focusing of the infiniteobject point, of the zoom lens in the sixteenth embodiment;

FIGS. 74A, 74B, 74C, and 74D are diagrams showing aberrationcharacteristics at the telephoto position, in focusing of the infiniteobject point, of the zoom lens in the sixteenth embodiment;

FIGS. 75A, 75B, 75C, and 75D are diagrams showing aberrationcharacteristics at the wide-angle position, in focusing of theshort-distance object point, of the zoom lens in the sixteenthembodiment;

FIGS. 76A, 76B, 76C, and 76D are diagrams showing aberrationcharacteristics at the middle position, in focusing of theshort-distance object point, of the zoom lens in the sixteenthembodiment;

FIGS. 77A, 77B, 77C, and 77D are diagrams showing aberrationcharacteristics at the telephoto position, in focusing of theshort-distance object point, of the zoom lens in the sixteenthembodiment;

FIG. 78 is an explanatory view showing an example of a pixel array of anelectronic image sensor used together with the zoom lens according tothe present invention;

FIG. 79 is a graph showing the transmittance characteristics of anexample of a near-infrared sharp-cutoff coat;

FIG. 80 is a graph showing the transmittance characteristics of anexample of a color filter provided on the exit side of a CCD coverglass, or another lens, to which the near-infrared cutoff coat isapplied;

FIG. 81 is a view showing an array of color filter elements of acomplementary mosaic color filter;

FIG. 82 is a graph showing an example of the wavelength characteristicsof the complementary mosaic color filter;

FIG. 83 is an explanatory view showing a modified example of a stop usedin the electronic imaging device according to the present invention;

FIG. 84 is an explanatory view showing an example of a light-amountadjusting means used in the electronic imaging device according to thepresent invention;

FIG. 85 is a perspective view showing a specific example where thelight-amount adjusting means of FIG. 84 is applied to the electronicimaging device according to the present invention;

FIG. 86 is an explanatory view showing another example of thelight-amount adjusting means applicable to the electronic imaging deviceaccording to the present invention;

FIG. 87 is an explanatory view showing still another example of thelight-amount adjusting means applicable to the electronic imaging deviceaccording to the present invention;

FIG. 88A is a view schematically showing the back side of a rotaryfocal-plane shutter adjusting light-receiving time, applicable to theelectronic imaging device according to the present invention;

FIG. 88B is a view schematically showing the right side of the rotaryfocal-plane shutter of FIG. 88A;

FIG. 89A is a view showing a state where an exposure aperture iscompletely covered by the blade of the rotary focal-plane shutter ofFIG. 88A;

FIG. 89B is a view showing a state where the left half of the exposureaperture is covered by the blade of the rotary focal-plane shutter ofFIG. 88A;

FIG. 89C is a view showing a state where the exposure aperture is fullyopened by the blade of the rotary focal-plane shutter of FIG. 88A;

FIG. 89D is a view showing a state where the right half of the exposureaperture is covered by the blade of the rotary focal-plane shutter ofFIG. 88A;

FIG. 90 is a view schematically showing one embodiment of a deformablemirror which is a reflective optical component used in the zoom lens ofthe present invention;

FIG. 91 is an explanatory view showing one aspect of electrodes used inthe deformable mirror of FIG. 90;

FIG. 92 is an explanatory view showing another aspect of electrodes usedin the deformable mirror of FIG. 90;

FIG. 93 is a view schematically showing another embodiment of thedeformable mirror which is the reflective optical component used in thezoom lens of the present invention;

FIG. 94 is a view schematically showing still another embodiment of thedeformable mirror which is the reflective optical component used in thezoom lens of the present invention;

FIG. 95 is a view schematically showing a further embodiment of thedeformable mirror which is the reflective optical component used in thezoom lens of the present invention;

FIG. 96 is an explanatory view showing the winding density of a coil inthe embodiment of FIG. 95;

FIG. 97 is a view schematically showing another embodiment of thedeformable mirror which is the reflective optical component used in thezoom lens of the present invention;

FIG. 98 is an explanatory view showing one example of an array of coilsin the embodiment of FIG. 97;

FIG. 99 is an explanatory view showing another example of an array ofcoils in the embodiment of FIG. 97;

FIG. 100 is an explanatory view showing an array of permanent magnetssuitable for the array of coils of FIG. 99 in the embodiment of FIG. 95;

FIG. 101 is a view schematically showing an imaging system which usesthe deformable mirror applicable as the reflective optical componenthaving a reflecting surface for bending the optical path of the zoomlens in another embodiment of the present invention, for example, animaging system used in a digital camera of a cellular phone, a capsuleendoscope, an electronic endoscope, a digital camera for personalcomputers, or a digital camera for PDAs;

FIG. 102 is a perspective front view showing a digital cameraincorporating the zoom lens of the present invention in a photographingoptical system;

FIG. 103 is a perspective rear view showing the digital camera of FIG.102;

FIG. 104 is a sectional view showing the internal structure of thedigital camera of FIG. 102;

FIG. 105 is a perspective front view showing a personal computer inwhich the zoom lens of the present invention is incorporated as anobjective optical system;

FIG. 106 is a sectional view showing the photographing optical systemincorporated in the personal computer of FIG. 105;

FIG. 107 is a side view showing the personal computer of FIG. 105;

FIG. 108A is a front view showing a cellular phone which has thephotographing optical system incorporating the zoom lens of the presentinvention;

FIG. 108B is side view showing the cellular phone of FIG. 108A; and

FIG. 108C is a sectional view showing the photographing optical systemhoused in the cellular phone of FIG. 108A.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Before undertaking the description of the embodiments, the constructionof function of the present invention will be explained.

In the imaging device of the present invention, the construction thatthe optical path (optical axis) of a zoom lens system is bent by areflective optical component, such as a mirror or a prism, is adoptedand various devices are used for its compactness.

The zoom lens system of the present invention has a fundamentalarrangement that a most object-side lens unit (hereinafter referred toas a first lens unit) includes, in order from the object side, anegative lens component, a reflecting surface (front surface mirror) forbending the optical path, and a positive lens component so that theseremain fixed when the magnification of the zoom lens system is changedand the focusing operation is performed, while a most image-side lensunit (hereinafter referred to as a last lens unit) has an asphericalsurface so that the lens unit remains fixed when the focusing operationis performed, and other lens units moved for changing the magnificationare interposed between the above two lens units. (Also, in the presentinvention, a lens component refers to a lens in which only the mostobject-side lens surface and the most image-side lens surface come incontact with air and air is not interposed between them. A single lensor a cemented lens is assumed to be one unit.)

However, when the reflecting surface (front surface mirror) for bendingthe optical path is placed in the first lens unit, the following twoproblems arise.

First, the distance to the entrance pupil is increased and individuallens elements constituting the first lens unit which have originallylarge diameters are further bulked. Consequently, it becomes difficultto determine whether the arrangement for bending the optical path can beused.

Second, a combined variable magnification ratio of individual lensunits, each located on the image side of the first lens unit andexercising a variable magnification function, approaches zero andbecomes low for the amount of movement of the lens units.

Here, a description is given of conditions for accomplishing pathbending.

When the reflecting surface (front surface mirror) for bending theoptical path is placed in the first lens unit, there is a tendency thatthe distance to the entrance pupil is necessarily increased, so that thediameter or size of each of optical elements constituting the first lensunit is bulked and it becomes hard to physically accomplish the pathbending.

The first lens unit is thus constructed with, in order from the objectside, the negative lens with a convex surface directed toward the objectside, the reflecting surface (front surface mirror) for bending theoptical path, and the positive lens, and thereby the distance to theentrance pupil is reduced.

Hence, in order to ensure a space for the path bending, the negativelens component and the positive lens component of the first lens unitare arranged at a distance from each other while having strong powers ofsome degree. Consequently, off-axis aberration, such as coma,astigmatism, or distortion, is naturally deteriorated, but suchaberration can be corrected by introducing an aspherical surface intothe last lens unit.

On the other hand, the amount of correction of off-axis aberration bythe aspherical surface of the last lens unit is conspicuously large, andwhen it is used in rear focusing, the off-axis aberration fluctuatesconsiderably. It is thus desirable that the last lens unit is made toremain fixed in focusing, and another path bending element in the systemis used in such a way that, for example, the shape of the reflectingsurface (front surface mirror) for bending the optical path is changedand controlled.

In order to physically accomplish the path bending, it is desirable tosatisfy Conditions (1) and (2), preferably Conditions (3) and (4),described below.1.0<−f11/√{square root over ((fw·fT))}<2.5   (1)1.4<f12/√{square root over ((fw·fT))}<3.2   (2)0.7<d/L<2.0   (3)1.55<npri   (4)where f11 is the focal length of the negative lens component in the mostobject-side lens unit, f12 is the focal length of the positive lenscomponent in the most object-side lens unit, fw is the focal length ofthe entire system at the wide-angle position of the zoom lens, fT is thefocal length of the entire system at the telephoto position of the zoomlens, d is an air-equivalent length measured along the optical axis fromthe image-side vertex of the negative lens component to the object-sidevertex of the positive lens component in the most object-side lens unit,L is the diagonal length of an effective imaging area of an electronicimage sensor, and npri is the refractive index of a medium at the d linein the case where the reflective optical component for bending theoptical path in the first lens unit is a prism. (Also, in the presentinvention, a lens component refers to a lens in which only the mostobject-side lens surface and the most image-side lens surface come incontact with air and air is not interposed between them. A single lensor a cemented lens is assumed to be one unit.)

In order to reduce the distance to the entrance pupil to make the pathbending physically possible, it is desirable to satisfy Conditions (1)and (2) so that the powers of lens elements on both sides of the firstlens unit are strengthened.

If the upper limit of each of Conditions (1) and (2) is overstepped, thedistance to the entrance pupil will remain long, and thus when anattempt is made to ensure a field angle to some degree, the diameter orsize of each of optical elements constituting the first lens unit isbulked and it becomes hard to physically accomplish the path bending.

Below the lower limit of each of Conditions (1) and (2), the diameter ofthe positive lens component of the first lens unit is bulked, andcorrection for off-axis aberration, such as coma, astigmatism, ordistortion, becomes difficult.

Condition (3) defines a length measured along the optical axis which isrequired to provide the reflecting surface (front surface mirror) forbending the optical path. It is favorable that the value of Condition(3) is as small as possible. Below the lower limit, the path bending isnot accomplished or a light beam contributing to image formation on animage periphery fails to satisfactorily reach the image plane. Inaddition, ghost is easily produced.

Beyond the upper limit of Condition (3), on the other hand, correctionfor off-axis aberration becomes difficult, like the case of Conditions(1) and (2).

From the above viewpoint, in order to reduce the air-equivalent length dof Condition (3), it is desirable that the path bending element of thefirst lens unit is constructed as a prism in which the entrance surfaceand the exit surface are flat or which has surfaces of curvaturesdifferent from those of lens surfaces of lenses located on both sidesthereof, and the refractive index of its medium satisfies Condition (4).

Below the lower limit of Condition (4), it becomes hard to physicallyaccomplish the path bending, or correction for off-axis aberrationbecomes difficult.

However, it is desirable that the upper limit of Condition (4) is takenas 1.9 and this value is not exceeded. Beyond the upper limit of 1.9, aprism of costly material must be used.

It is more desirable to satisfy at least one of the followingconditions:1.2<−f11/√{square root over ((fw·fT))}<2.2   (1′)1.5<f12/√{square root over ((fw·fT))}<3.0   (2′)0.8<d/L<1.8   (3′)1.65<npri   (4′)

It is most desirable to satisfy at least one of the followingconditions:1.4<−f11/√{square root over ((fw·fT))}<1.9   (1″)1.6<f12/√{square root over ((fw·fT))}<2.8   (2″)0.9<d/L<1.6   (3″)1.75<npri   (4″)

As mentioned above, when the negative lens component and the positivelens component of the first lens unit are arranged at a distance fromeach other while having strong powers of some degree, there is atendency that the amount of fluctuation of chromatic aberration ofmagnification caused by the magnification change is increased. It is,therefore, favorable to satisfy the following conditions:26<ν1N   (5)−0.15<√{square root over ((fw·fT))}/f1<0.5   (6)where ν1N is the Abbe's number, at the d line, of the medium of thenegative lens component located on the object side of the first lensunit and f1 is the focal length of the first lens unit.

Below the lower limit of Condition (5), the fluctuation of chromaticaberration of magnification where the magnification is changed becomesprominent, which is unfavorable. Also, the upper limit of Condition (5)is not restricted.

Beyond the upper limit of Condition (6), correction for off-axisaberration or chromatic aberration becomes difficult, and in particular,even when Condition (5) is satisfied, correction for chromaticaberration of magnification may become difficult.

Below the lower limit of Condition (6), the fluctuation of aberrationcaused by the movement of the lens unit for the magnification change maybecome prominent.

It is more favorable to satisfy one of the following conditions:30<ν1N   (5′)−0.1<√{square root over ((fw·fT))}/f1<0.4   (6′)

It is most favorable to satisfy one of the following conditions:33<ν1N   (5″)0.05<√{square root over ((fw·fT))}/f1<0.3   (6″)

From the above description, it is desirable that the zoom lens of thepresent invention is constructed so that the most object-side lens unitremains fixed when the magnification is changed and the focusingoperation is performed, and includes, in order from the object side, thenegative lens component, the reflective optical component for bendingthe optical path, and the positive lens component, while the mostimage-side lens unit has an aspherical surface and remains fixed whenthe focusing operation is performed, and lens units moved for changingthe magnification are interposed between the above two lens units.

Subsequently, reference is made to the techniques of the magnificationchange and the focusing operation of the zoom lens which has thereflective optical component (front surface mirror) for bending theoptical path. For the magnification change, the following three systemsare considered.

1. A zoom system comprising, in order from the object side, a first lensunit with negative refracting power, including a reflective opticalcomponent (front surface mirror) and remaining fixed; a second lens unitwith positive refracting power, moved toward only the object side whenthe magnification is changed, extending from the wide-angle position tothe telephoto position; a third lens unit (which can be moved when themagnification is changed and the focusing operation is performed) movedto differ from the second lens unit when the magnification is changed;and a last lens unit having an aspherical surface and remaining fixed.

2. A zoom system comprising, in order from the object side, a first lensunit with positive refracting power, including a reflective opticalcomponent (front surface mirror) and remaining fixed; a second lens unitwith negative refracting power, moved toward only the image side whenthe magnification is changed, extending from the wide-angle position tothe telephoto position; a third lens unit moved in only a directionopposite to that of the second lens unit when the magnification ischanged; and a last lens unit which can be moved when the focusingoperation is performed.

3. A zoom system comprising, in order from the object side, a first lensunit with positive refracting power, including a reflective opticalcomponent (front surface mirror) and remaining fixed; a second lens unitwith negative refracting power, moved back and forth on the image sideto follow a convex path, when the magnification is changed, extendingfrom the wide-angle position to the telephoto position; a third lensunit with positive refracting power, moved toward only the object sidewhen the magnification is changed, extending from the wide-angleposition to the telephoto position; and a last lens unit having anaspherical surface and remaining fixed.

The system 1 has the disadvantage that, in order to ensure the variablemagnification ratio, it is hard to impart the power to the third lensunit and the amount of movement is extremely increased. An increase ofthe amount of movement renders focusing slow and raises powerconsumption. Consequently, in the present invention, the system 2 or 3is adopted.

The system 2 has a difficulty about a reduction in the distance to theentrance pupil or correction for off-axis aberrations or chromaticaberration of magnification because the power of the negative lenscomponent located on the object side of the first lens unit is weak orthe power of the positive lens component on the image side of the firstlens unit is extremely strong.

The system 3, by contrast, has no problem of correction for aberration,zooming, or size with the exception of the case where it is necessary toensure the space for moving the second lens unit in focusing. Forfocusing, the profile of the surface of the reflective optical component(front surface mirror) for bending the optical path is changed andcontrolled, and thereby its defect can be obviated.

Thus, in the present invention, the system 3 is adopted. Specifically,the zoom lens has, in order from the object side, the first lens unitprovided with the reflective optical component for bending the opticalpath, remaining fixed when the magnification is changed; the second lensunit with negative refracting power, moved when the magnification ischanged; the third lens unit with positive refracting power, moved whenthe magnification is changed; and the last lens unit. When themagnification is changed, extending from the wide-angle position to thetelephoto position, in focusing of the infinite object point, the secondlens unit is constructed so that it is moved (back and forth) along theoptical axis on the image side to follow a convex path. By doing so, thedefects of the systems 2 and 3 can be obviated.

It is further desirable to satisfy the following conditions:0.3<−βRw<0.8   (7)0.8<fRw/√{square root over ((fw·fT))}<1.8   (8)where βRw is a combined magnification of the third lens unit and thelens unit subsequent thereto at the wide-angle position in focusing ofthe infinite object point and fRw is a combined focal length of thethird lens unit and the lens unit subsequent thereto at the wide-angleposition in focusing of the infinite object point.

Below the lower limit of Condition (7), the variable magnification ratiowhich is high enough in the entire system of the zoom lens is notobtained, or the space for lens movement becomes extremely wide and thesize is bulked.

Beyond the upper limit of Condition (7), although of great rarity intheory, a wide space for lens movement is required.

Below the lower limit of Condition (8), the combined magnification ofthe third lens unit and the lens unit subsequent thereto is lowered andthereby variable magnification efficiency is impaired.

Beyond the upper limit of Condition (8), on the other hand, the combinedfocal length of the third lens unit and the lens unit subsequent theretois increased and thereby variable magnification efficiency is impaired.

It is more desirable to satisfy one of the following conditions:0.35<−βRw<0.75   (7′)0.9<fRw/√{square root over ((fw·fT))}<1.6   (8′)

It is most desirable to satisfy one of the following conditions:0.4<−βRw<0.7   (7″)1.0<fRw/√{square root over ((fw·fT))}<1.5   (8″)

Also, although the focusing operation in the zoom lens of the presentinvention may be usually performed by moving any lens unit of the zoomlens, it is favorable that the focusing operation is performed bychanging and controlling the shape of the reflecting surface in thefirst lens unit in order to decrease the amount of drive of the lensunits in the lens barrel of the zoom lens to bring compactness.

For example, it is desirable that the reflecting surface is constructedwith a thin film with which a metal or dielectric is coated; the thinfilm is connected to a power source through a plurality of electrodesand variable resistors; an arithmetical unit controlling the resistancevalues of the variable resistors is provided to control the distributionof electrostatic forces applied to the thin film; and thereby theprofile of the reflecting surface can be changed. It is advantageousthat a deformable reflecting surface is small in view of itsproductivity and controllability.

In the focusing technique relative to the short-distance object point,it is desirable that the second lens unit is shifted to the object side,or another lens unit moved for focusing is provided between the thirdlens unit and the most image-side lens unit and is moved along theoptical axis.

Where the second lens unit is shifted to the object side as the focusingtechnique relative to the short-distance object point, it is favorableto satisfy the following condition:0.16<D12min/√{square root over ((fw·fT))}<0.26   (9)where D12min is a minimum value available between the first lens unitand the second lens unit in focusing of the infinite object point.

The second lens unit is capable of focusing on a considerableshort-distance object point with a slight amount of movement. Below thelower limit of Condition (9), however, a space required to move thesecond lens unit for focusing becomes insufficient, and the second lensunit interferes with the first lens unit or ceases to focus on ashorter-distance object point.

Beyond the upper limit of Condition (9), on the other hand, the distanceto the entrance pupil is liable to be increased, and correction foraberration and the maintenance of magnification may be obstructed in anattempt to reduce the distance.

It is more favorable to satisfy the following condition:0.17<D12min/√{square root over ((fw·fT))}<0.24   (9′)

It is most favorable to satisfy the following condition:0.18<D12min/√{square root over ((fw·fT))}<0.22   (9″)

Where another lens unit moved for focusing is provided between the thirdlens unit and the most image-side lens unit and is moved along theoptical axis, it is desirable to satisfy the following condition:1.0<|fF|/√{square root over ((fw·fT))}<6.0   (10)where fF is the focal length of a lens unit moved along the optical axisin the focusing operation of the short-distance object point, interposedbetween the third lens unit and the most image-side lens unit.

Beyond the upper limit of Condition (10), the amount of movement of thelens unit moved in focusing is increased, which is unfavorable.

Below the lower limit of Condition (10), on the other hand, correctionfor off-axis aberrations becomes difficult, or the amount of fluctuationof the position of the entrance pupil is exceedingly increased.Consequently, shading is liable to be produced.

It is more desirable to satisfy the following condition:1.5<|fT|/√{square root over ((fw·fT))}<5.0   (10′)

It is still more desirable to satisfy the following condition:2.0<|fT|/√{square root over ((fw·fT))}<4.0   (10″)

Subsequently, a description is given of techniques for favorablyachieving the maintenance of magnification and correction foraberration.

The arrangement of the third lens unit is deeply concerned with these. Alarger number of lenses, although advantageous, offer an obstacle in theway of compactness to be achieved for the most useful purpose. Hence, itis important that the lens unit is constructed with the smallestpossible number of lenses. The third lens unit, which has the variablemagnification function, is moved toward only the object side when themagnification is changed, extending from the wide-angle position to thetelephoto position. In correction for aberration, three lenses includingone positive lens and one negative lens are enough for the number oflenses required for constituting the third lens unit. However, adecentering sensitivity of the negative lens (the increment ofaberration to the amount of unit decenteration) is high. Consequently,it is desirable that the negative lens is cemented to either positivelens in the third lens unit.

Thus, there are the following three ways that the third lens unit isconstructed with, in order from the object side,

A. a single lens and a cemented lens component with a positive lens anda negative lens,

B. a cemented lens component with a positive lens and a negative lens,and a single lens, or

C. a three-cemented-lens component with a positive lens, a negativelens, and a positive lens.

In order to minimize spaces for movement of the second lens unit and thethird lens unit, moved when the magnification is changed, it isdesirable that the magnification of the third lens unit is −1× at themiddle focusing distance. However, when the first lens unit of thepresent invention is constructed as mentioned above, the image pointproduced by the system before the third lens unit, namely the objectpoint relative to the third lens unit, is necessarily moved fartheraway, toward the object side, than in a usual state. As a result, themagnification of the third lens unit approaches zero, and much space formovement is required.

However, when the third lens unit is constructed like Item A, there isthe advantage that the primary principal point is located closer to theobject side and thus its defect can be obviated. Similarly, thesecondary principal point is also located closer to the object side andthus unnecessary space is not provided in the rear of the third lensunit. As such, a length in the rear of the path bending element can beeffectively reduced.

When the third lens unit is constructed like Item A, on the other hand,there are advantages that the exit pupil tends to become closer and theamount of change of the F value by the magnification change is so largethat the lens unit is liable to undergo the influence of diffraction atthe telephoto position.

Thus, when the third lens unit is constructed like Item A, this lensunit is easily downsized and is suitable for use of a largish imagesensor.

On the other hand, when the third lens unit is constructed like Item Bor C, the length conversely becomes longer than in Item A, but the lensunit has advantages for the position of the exit pupil and the change ofthe F value where the magnification is changed, and thus is suitable foruse of a smallish image sensor.

Also, it is desirable to satisfy Condition (11A) described below whenthe third lens unit is constructed like Item A and Condition (11B)described below when the third lens unit is constructed like Item B.0.4<R _(C3) /R _(C1)<0.85   (11A)0.8<R _(C3) /R _(C1)<1.3   (11B)where R_(C3) is the radius of curvature, on the optical axis, of themost image-side surface of a cemented lens component in the third lensunit and R_(C1) is the radius of curvature, on the optical axis, of themost object-side surface of the cemented lens component in the thirdlens unit.

Beyond the upper limit of each of Conditions (11A) and (11B), the lensunit is advantageous for correction for spherical aberration, coma, orastigmatism in the entire system, but it has little effect of themoderation of the decentering sensitivity on cementation.

Below the lower limit of each of Conditions (11A) and (11B), correctionfor spherical aberration, coma, or astigmatism in the entire system isliable to become difficult.

Also, it is more desirable to satisfy Condition (11′A) described belowwhen the third lens unit is constructed like Item A and Condition (11′B)described below when the third lens unit is constructed like Item B.0.5<R _(C3) /R _(C1)<0.8   (11′A)0.85<R _(C3) /R _(C1)<1.2   (11′B)

It is most desirable to satisfy Condition (11″A) described below whenthe third lens unit is constructed like Item A and Condition (11″B)described below when the third lens unit is constructed like Item B.0.6<R _(C3) /R _(C1)<0.7   (11″A)0.9<R _(C3) /R _(C1)<1.1   (11″B)

In correction for chromatic aberration, it is favorable to satisfyConditions (12A) and (13A) described below (when the third lens unit isconstructed like Item A), or Conditions (12B) and (13B) described below(when the third lens unit is constructed like Item B).−0.3<L/R _(C2)<1.0   (12A)15<ν_(CP)−ν_(CN)   (13A)−0.1<L/R _(C2)<0.8   (12B)15<ν_(CP)−ν_(CN)   (13B)where L is the diagonal length (mm) of an image sensor used. Also, it ispremised that the image sensor is used in such a way that the fieldangle at the wide-angle position is 50° or more. R_(C2) is the radius ofcurvature, on the optical axis, of the interface of the cemented lenscomponent in the third lens unit, ν_(CP) is the Abbe's number of themedium of the positive lens of the cemented lens component in the thirdlens unit, and ν_(CN) is the Abbe's number of the medium of the negativelens of the cemented lens component in the third lens unit.

Below the lower limit of each of Conditions (12A) and (12B), the lensunit is advantageous for correction for axial chromatic aberration orchromatic aberration of magnification, but spherical aberration orchromatic aberration is liable to be produced. In particular, althoughspherical aberration at a reference wavelength can be favorablycorrected, spherical aberration at a short wavelength is overcorrected,giving rise to a blotted image of color, which is unfavorable.

Below the lower limit of each of Conditions (12A) and (12B), axialchromatic aberration or chromatic aberration of magnification isinsufficiently corrected, and spherical aberration at the shortwavelength is liable to be undercorrected.

Below the lower limit of Condition (13A) or (13B), axial chromaticaberration is liable to be undercorrected.

Also, a combination of media such as to exceed the upper limit ofCondition (13A) or (13B) does not exist in the natural world.

It is more favorable to satisfy at least one of Conditions (12′A) and(13′A) described below when the third lens unit is constructed like ItemA, or at least one of Conditions (12′B) and (13′B) described below whenthe third lens unit is constructed like Item B.−0.1<L/R _(C2)<0.8   (12′A)20<ν_(CP)−ν_(CN)   (13′A)0<L/R _(C2)<0.6   (12′B)20<ν_(CP)−ν_(CN)   (13′B)

It is most favorable to satisfy at least one of Conditions (12″A) and(13″A) described below when the third lens unit is constructed like ItemA, or at least one of Conditions (12″B) and (13″B) described below whenthe third lens unit is constructed like Item B.0.1<L/R _(C2)<0.6   (12″A)25<ν_(CP)−ν_(CN)   (13″A)0.15<L/R _(C2)<0.4   (12″B)25<ν_(CP)−ν_(CN)   (13″B)

Each of Conditions (13A), (13′A), (13″A), (13B), (13.′B), and (13″B) maybe set so that the value of ν_(CP)−ν_(CN) does not exceed 90. Acombination of media such as to exceed the upper limit of 90 does notexist in the natural world.

It is further favorable to set the condition so that the value ofν_(CP)−ν_(CN) does not exceed 60. If the upper limit of 60 is exceeded,a material used becomes expensive.

On the other hand, when the third lens unit is constructed like Item C,it is desirable to satisfy at least one of Conditions (14)-(18)described below.−4.0<(R _(CF) +R _(CR))/(R _(CF) −R _(CR))<0   (14)where R_(CF) is the radius of curvature, on the optical axis, of themost object-side surface of the three-cemented-lens component and R_(CR)is the radius of curvature, on the optical axis, of the most image-sidesurface of the three-cemented-lens component.0.6<Dc/fw<1.8   (15)where Dc is a distance measured along the optical axis, form the mostobject-side surface of the three-cemented-lens component to the mostimage-side surface thereof.0.002/mm²<Σ|(1/Rci)−(1/Rca)|²<0.05/mm²   (16)where Rci is the radius of curvature, on the optical axis, of the i-thinterface of the three-cemented-lens component from the object side andRca is m/Σ|(1/Rci)|(i=1 . . . m, where m is 2 of the number ofinterfaces).5×10⁻⁵<Σ|(1/νcj+1)−(1/νcj)|²<4×10⁻³   (17)where νcj is the Abbe's number, at the d line, of the i-th medium of thethree-cemented-lens component from the object side (j=1 . . . n−1, wheren is 3 of the number of lenses to be cemented).0.005<Σ|ncj+1−ncj| ²<0.5   (18)where ncj is the refractive index, at the d line, of the i-th medium ofthe three-cemented-lens component from the object side.

Condition (14) defines a condition of the shape factor of a cementedlens component which has m interfaces (m≧2) in the lens units moved whenthe magnification is changed.

Below the lower limit of Condition (14), it becomes difficult to ensurethe variable magnification ratio or to reduce the entire length in aworking state (which is related to a volume where the lens barrel iscollapsed). Beyond the upper limit of Condition (14), even though anaspherical surface is introduced, correction for spherical aberration orcoma becomes difficult.

Condition (15) defines a condition of a distance (thickness), along theoptical axis, between the most object-side surface and the mostimage-side surface of a cemented lens component which has m interfaces(m≧2) in the lens units moved when the magnification is changed.

Beyond the upper limit of Condition (15), the thickness of the entiresystem where the lens barrel is collapsed is not reduced. Below thelower limit of Condition (15), the radius of curvature of each interfacecannot be reduced, and the effect of cementation (for instance,correction for chromatic aberration) cannot be brought about.

Condition (16) defines a condition for bringing about the effect ofcorrection for aberration in each interface.

Beyond the upper limit of Condition (16), this is advantageous forcorrection for aberration, but makes the system liable to exceed theupper limit of Condition (15).

Below the lower limit of Condition (16), this is advantageous forreducing the thickness of the lens system, but the effects of correctionfor aberrations are mutually cancelled, which is unfavorable.

Condition (17) defines a condition of correction for chromaticaberration of a cemented lens component which has m interfaces (m>2) inthe lens units moved when the magnification is changed.

Below the lower limit of Condition (17), correction for chromaticaberration becomes insufficient. Beyond the upper limit of Condition(17), chromatic aberration may be overcorrected.

Condition (18) defines a condition of correction for sphericalaberration, coma, or curvature of field of a cemented lens componentwhich has m interfaces (m≧2) in the lens units moved when themagnification is changed.

Below the lower limit of Condition (18), correction for sphericalaberration or coma becomes insufficient, and the Petzval sum is liableto take a large negative value. Beyond the upper limit of Condition(18), the high-order component of spherical aberration or coma is liableto be produced, and the Petzval sum is liable to take a large positivevalue.

Also, Condition (17) or (18) serves to define the case where therefractive index is low and the Abbe's number is high with respect tothe positive lens or the negative lens.

Instead of Conditions (14)-(18), when the following conditions are set,a slimmer design and higher performance can be achieved:−3.0<(R _(CF) +R _(CR))/(R _(CF) −R _(CR))<−0.3   (14′)0.8<Dc/fw<1.6   (15′)0.004/mm²<Σ|(1/Rci)−(1/Rca)|²<0.04/mm²   (16′)1×10⁻⁴<Σ|(1/νcj+1)−(1/νcj)|²<3×10⁻³   (17′)0.01<Σ|ncj+1−ncj| ²<0.4   (18′)

Instead of Conditions (14)-(18), when the following conditions arefurther set, the slimmest design and highest performance can beachieved:−2.0<(R _(CF) +R _(CR))/(R _(CF) −R _(CR))<−0.5   (14″)1.0<Dc/fw<1.4   (15″)0.006/mm²<Σ|(1/Rci)−(1/Rca)|²<0.03/mm²   (16″)2×10⁻⁴<Σ|(1/νcj+1)−(1/νcj)|²<2×10⁻³   (17″)0.02<Σ|ncj+1−ncj| ²<0.3   (18″)

In the zoom lens of the present invention, it is desirable that anaspherical surface is introduced into the negative lens componentlocated on the object side in the first lens unit.

It is desirable that the positive lens component located on the imageside in the first lens unit satisfies the following condition:−2.0<(R _(IPF) +R _(IPR))/(R _(IPF) −R _(IPR))<1.0   (19)where R_(IPF) is the radius of curvature, on the optical axis, of theobject-side surface of the positive lens component of the mostobject-side lens unit and R_(IPR) is the radius of curvature, on theoptical axis, of the image-side surface of the positive lens componentof the most object-side lens unit.

Beyond the upper limit of Condition (19), high-order chromaticaberration of magnification is liable to be produced. Below the lowerlimit of Condition (19), the distance to the entrance pupil is liable tobe increased.

It is more desirable to satisfy the following condition:−1.7<(R _(IPF) +R _(IPR))/(R _(IPF) −R _(IPR))<0.5   (19′)

It is most desirable to satisfy the following conditions:−1.4<(R _(IPF) +R _(IPR))/(R _(IPF) −R _(IPR))<0.1   (19″)

In the second lens unit, the focal length is long, and thus theconstruction of two lens components, a negative lens component and apositive lens component, arranged in this order form the object side, issatisfactory. Moreover, lens cementation allows the decenteringsensitivity to be reduced, which is favorable. It is desirable that thecemented lens component satisfies the following condition:−1.5<(R _(2F) +R _(2R))/(R _(2F) −R _(2R))<0.8   (20)where R_(2F) is the radius of curvature, on the optical axis, of themost object-side surface of the second lens unit (the cemented lenscomponent) and R_(2R) is the radius of curvature, on the optical axis,of the most image-side surface of the second lens unit (the cementedlens component).

Beyond the upper limit of Condition (20), the distance to the entrancepupil is liable to be increased. Below the lower limit of Condition(20), various off-axis aberrations are liable to be produced. It is moredesirable to satisfy the following condition:−1.2<(R _(2F) +R _(2R))/(R _(2F) −R _(2R))<0.5   (20′)

It is most desirable to satisfy the following condition:−0.9<(R _(2F) +R _(2R))/(R _(2F) −R _(2R))<0.2   (20″)

In the zoom lens of the system of bending the optical path as in thepresent invention, the degree of a compact design of the optical systeminvolved in compactness of the image sensor is higher than in the zoomlens of the lens barrel collapsing system.

Thus, in order to make the camera slimmer, it is effective that the zoomlens of the present invention is used by applying a small electronicimage sensor such as to have a relationship satisfying the followingcondition:F≧a   (21)with respect to a horizontal pixel pitch a (μm) and an open F value atthe wide-angle position of the zoom lens. In this case, the followingconsideration is more effective.

As the image sensor becomes small, the pixel pitch also becomesproportionally small, and the deterioration of image quality by theinfluence of diffraction ceases to be negligible. In particular, whenthe image sensor is reduced in size so that the relationship between theopen F value at the wide-angle position and the horizontal pixel pitch a(μm) of the electronic image sensor used satisfies Condition (21), onlythe open F value can be used.

Hence, the aperture stop determining the F value is designed so that itsinside diameter is made constant and an insertion in, or removal from,the optical path, or replacement is not made. In addition, the aperturestop is placed so that at least one of refracting surfaces adjacent tothe aperture stop is a convex surface directed toward the aperture stop(in the present invention, a refracting surface adjacent to the aperturestop on the image side corresponds thereto), and the point ofintersection of a perpendicular line drawn to the optical axis from theaperture stop with the optical axis is located 0.5 mm or less from thevertex of the convex surface, or the convex surface intersects or comesin contact with the inside diameter portion of an aperture stop memberincluding the back surface of the aperture stop. By doing so, much spacefor the aperture stop, formerly would have been required, becomesunnecessary and the space can be considerably saved. This largelycontributes to compactness.

For the adjustment of the amount of light, it is good practice to use avariable transmittance means instead of the aperture stop. The variabletransmittance means can be introduced into any position of the opticalpath, and thus it is favorable to place the means in originallysufficient space. In particular, in the present invention, it isfavorable to insert the means between the lens unit moved for themagnification change and the image sensor. For the variabletransmittance means, the means in which the transmittance can be changedby the voltage may be used, or a plurality of filters having differenttransmittances may be combined by an insertion in, or removal from, theoptical path, or replacement. It is desirable that a shutter whichadjusts light-receiving time of a light beam introduced into theelectronic image sensor is placed in space independent of that of theaperture stop.

In the relationship between the open F value at the wide-angle positionand the horizontal pixel pitch a (μm) of the electronic image sensorused, when Condition (21) is satisfied, an optical low-pass filter maybe eliminated. That is, any medium on the optical path interposedbetween the zoom lens system and the image sensor may be thought of asair or a non-crystalline medium. This is because there is littlefrequency component which is capable of producing return strain becauseof the deterioration of imaging characteristics by diffraction andgeometrical aberration. Alternatively, each optical element interposedbetween the zoom lens system and the image sensor may be constructed sothat any medium interface is nearly flat and the optical system has noconverting function of spatial frequency characteristics like theoptical low-path filter.

Also, it is desirable that the zoom lens used in the present inventionsatisfies the following condition:1.8<fT/fw   (22)

Below the lower limit of Condition (22), the variable magnificationratio of the entire zoom lens system becomes smaller than 1.8. It ismore desirable that the value of fT/fw does not exceed 5.5. Beyond 5.5,the variable magnification ratio is increased, and the amount ofmovement of the lens unit moved when the magnification is changedbecomes so large that oversizing is caused in a direction in which theoptical path is bent and a compact imaging device ceases to beachievable.

The electronic image sensor used in the present invention is designed onthe premise that the full field angle at the wide-angle position is 55°or more. An angle of 55° is the full field angle at the wide-angleposition usually required for the electronic imaging device.

It is desirable that the field angle at the wide-angle position in theelectronic imaging device is 80° or less. If the field angle at thewide-angle position exceeds 80° , distortion will be liable to beproduced, and it becomes difficult to design the first lens unit to becompact. Consequently, a slim design of the electronic imaging devicebecomes difficult.

Subsequently, reference is made to requirements for reducing thethickness of an infrared cutoff filter.

In the electronic imaging device, the infrared absorbing filter ofconstant thickness is usually placed on the object side of the imagesensor so that infrared light is not incident on the imaging plane.

Consider the infrared absorbing filter to be replaced with a coatinghaving no thickness in order to make the optical system short or slim.In this case, of course, the thickness is reduced accordingly, but thereis the secondary effect.

When a near-infrared sharp-cutoff coat in which a transmittance is 80%or more at a wavelength of 600 nm and the transmittance is 8% or less ata wavelength of 700 nm is introduced on the object side of the imagesensor located behind the zoom lens system, the transmittance in anear-infrared region of more than 700 nm wavelengths becomes lower thanin the absorbing type and the transmittance on the red side becomesrelatively high. The tendency of magenta on the blue-violet side whichis a defect of a solid-state image sensor, such as a CCD, having acomplementary mosaic color filter is moderated by gain adjustment, andcolor reproduction like a solid-state image sensor, such as a CCD,having a primary-color filter can be obtained. Moreover, colorreproduction that has a high reflectance in the near-infrared region,like plants or human skin, is improved.

That is, it is desirable to satisfy the following conditions:τ600/τ550 ≧0.8   (23)τ700/τ550 ≦0.08   (24)where τ600 is a transmittance at a wavelength of 600 nm, τ550 is atransmittance at a wavelength of 550 nm, and τ700 is a transmittance ata wavelength of 700 nm.

It is more desirable to satisfy the following conditions:τ600/τ550 ≧0.85   (23′)τ700/τ550 ≦0.05   (24′)

It is most desirable to satisfy the following conditions:τ600/τ550 ≧0.9   (23″)τ700/τ550 ≦0.03   (24″)

Another defect of the solid-state image sensor, such as the CCD, is thatthe sensitivity to a wavelength of 550 nm in a near-ultraviolet regionis much higher than that of the human eye. This gives rise to aconsiderable color blot at the edge of an image due to chromaticaberration in the near-ultraviolet region. In particular, when theoptical system is downsized, a vital result is brought about. Thus, whenan absorber or reflector such that the ratio of the transmittance (τ400)at a wavelength of 400 nm to the transmittance (τ550) at a wavelength of550 nm is below 0.08, and the ratio of the transmittance (τ440) at awavelength of 440 nm to the transmittance (τ550) at a wavelength of 550nm is above 0.4, is introduced into the optical path, a noise, such asthe color blot, is lessened significantly without losing the wavelengthregion required for color reproduction (while holding good colorreproduction).

That is, it is desirable to satisfy the following conditions:τ400/τ550 ≧0.08   (25)τ440/τ550 ≦0.4   (26)

It is more desirable to satisfy the following conditions:τ400/τ550 ≧0.06   (25′)τ440/τ550 ≦0.5   (26′)

It is most desirable to satisfy the following conditions:τ400/τ550 ≧0.04   (25″)τ440/τ550 ≦0.6   (26″)

Also, it is favorable that such a filter is located between the imagingoptical system and the image sensor.

On the other hand, in the complementary color filter, because of themagnitude of transmission light energy, a substantial sensitivity ishigher than in a CCD with a primary-color filter and resolution isadvantageous. Hence, there is a great merit where a small-sized CCD isused.

Also, by properly combining the above conditions and arrangements, agood electronic imaging device can be constructed.

In each of the above conditions, only the upper limit or lower limit maybe set to a corresponding upper limit or lower limit of a more favorablecondition. A corresponding value of each of conditions in theembodiments mentioned later may be set to the upper or lower limit.

In accordance with the drawings, the embodiments of the presentinvention will be described below.

First Embodiment

FIG. 1 shows an optical arrangement of the first embodiment of the zoomlens according to the present invention. FIGS. 2A, 2B, and 2C showoptical arrangements at wide-angle, middle, and telephoto positions,respectively, in the first embodiment. FIGS. 3A-3D show aberrationcharacteristics at the wide-angle position in the first embodiment.FIGS. 4A-4D show aberration characteristics at the middle position inthe first embodiment. FIGS. 5A-5D show aberration characteristics at thetelephoto position in the first embodiment.

The electronic imaging device shown in FIG. 1 has, in order from theobject side, a zoom lens and a CCD which is an electronic image sensor.In this figure, reference symbol I represents the imaging plane of theCCD. A plane-parallel CCD cover glass CG is interposed between the zoomlens and the imaging plane I.

The zoom lens comprises, in order from the object side, a first lensunit G1, a second lens unit G2 which is a first moving lens unit, anaperture stop S, a third lens unit G3 which is a second moving lensunit, and a fourth lens unit G4.

The first lens unit G1 includes, in order from the object side, anegative meniscus lens L1 ₁ with a convex surface directed toward theobject side, a reflective optical component R1 having a reflectingsurface for bending the optical path, and a biconvex positive lens L1 ₂.

The reflective optical component R1 is constructed as a front surfacemirror bending the optical path by 90°. The reflecting surface of thefront surface mirror is designed to be deformable so that the profile ofthe reflecting surface is changed and thereby the focusing operation isperformed.

Also, the aspect ratio of an effective imaging area in each of theembodiments of the present invention is 3:4, and the optical path islaterally bent.

The second lens unit G2 includes, in order from the object side, acemented lens with a biconcave negative lens L2 ₁ and a positivemeniscus lens L2 ₂ with a convex surface directed toward the objectside, having negative refracting power as a whole.

The third lens unit G3 includes, in order from the object side, acemented lens with a biconvex positive lens L3 ₁ and a biconcavenegative lens L3 ₂, and a positive meniscus lens L3 ₃ with a convexsurface directed toward the object side, having positive refractingpower as a whole.

The fourth lens unit G4 includes a positive meniscus lens L4, with aconcave surface directed toward the object side.

When the magnification of the zoom lens is changed, extending from thewide-angle position to the telephoto position, the first lens unit G1and the fourth lens unit G4 remain fixed; the second lens unit G2 ismoved back and forth on the image side to follow a convex path (that is,after being moved toward the image side to widen once spacing betweenthe first lens unit G1 and the second lens unit G2, narrows the spacingwhile moving toward the object side); and the third lens unit G3 ismoved toward the object side only, together with the aperture stop S.

The first lens unit G1 and the fourth lens unit G4 remain fixed evenwhen the focusing operation is performed.

Aspherical surfaces are provided to the image-side surface of thenegative meniscus lens L1 ₁ with a convex surface directed toward theobject side in the first lens unit G1, both surfaces of the positivemeniscus lens L3 ₃ with a convex surface directed toward the object sidein the third lens unit G3, and the image-side surface of the positivemeniscus lens L4 ₁ with a concave surface directed toward the objectside, constituting the fourth lens unit G4.

Subsequently, numerical data of optical members constituting the zoomlens of the first embodiment are shown below.

Also, in the numerical data of the first embodiment, r₁, r₂, . . .denote radii of curvature of individual lens surfaces; d₁, d₂, . . .denote thicknesses of individual lenses or air spacings between them;n_(d1), n_(d2), . . . denote refractive indices of individual lenses atthe d line; ν_(d1), ν_(d2), . . . denote Abbe's numbers of individuallenses; Fno denotes an F-number; f denotes the focal length of theentire system; and D0 denotes a distance from an object to a firstsurface.

Also, when z is taken as the coordinate in the direction of the opticalaxis, y is taken as the coordinate normal to the optical axis, Krepresents a conic coefficient, and A₄, A₆, A₈, and A₁₀ representaspherical coefficients, the configuration of each of the asphericalsurfaces is expressed by the following equation:z=(y ² /r)/[1+{1−(1+K)(y/r)²}^(1/2) ]+A ₄ y ⁴ +A ₆ y ⁶ +A ₈ y ⁸ +A ₁₀ y¹⁰

These symbols hold for the numerical data of the embodiments to bedescribed later.

Also, the third and fourth surfaces in the numerical data are given asvirtual planes. A prism with a refractive index of 1 is assumed as thereflective optical component having the reflecting surface for bendingthe optical path and is designed to have an entrance surface and an exitsurface, but actually it is air spacing.

Numerical data 1 r₁ = 61.5439 d₁ = 0.7000 n_(d1) = 1.80610 ν_(d1) =40.92 r₂ = 6.2081 (aspherical) d₂ = 1.7000 r₃ = ∞ d₃ = 6.8000 r₄ = ∞ d₄= 0.1500 r₅ = 12.7178 d₅ = 1.5500 n_(d5) = 1.72916 ν_(d5) = 54.68 r₆ =−72.0943 d₆ = D6 r₇ = −9.2239 d₇ = 0.7000 n_(d7) = 1.69680 ν_(d7) =55.53 r₈ = 6.5000 d₈ = 1.3500 n_(d8) = 1.84666 ν_(d8) = 23.78 r₉ =18.7314 d₉ = D9 r₁₀ = ∞ (stop) d₁₀ = 0 r₁₁ = 4.7900 d₁₁ = 3.0000 n_(d11)= 1.74320 ν_(d11) = 49.34 r₁₂ = −8.0000 d₁₂ = 0.7000 n_(d12) = 1.84666ν_(d12) = 23.78 r₁₃ = 11.8703 d₁₃ = 0.3000 r₁₄ = 8.3986 (aspherical) d₁₄= 1.0000 n_(d14) = 1.69350 ν_(d14) = 53.21 r₁₅ = 19.5740 (aspherical)d₁₅ = D15 r₁₆ = ∞ (position of d₁₆ = 4.4000 variable transmittance meansor shutter) r₁₇ = −6.4029 d₁₇ = 1.0000 n_(d17) = 1.58313 ν_(d17) = 59.38r₁₈ = −5.3597 (aspherical) d₁₈ = 0.7000 r₁₉ = ∞ d₁₉ = 0.6000 n_(d19) =1.51633 ν_(d19) = 64.14 r₂₀ = ∞ d₂₀ = D20 r₂₁ = ∞ (imaging plane) d₂₁ =0 Aspherical coefficients Second surface K = 0 A₂ = 0 A₄ = −6.3011 ×10⁻⁴ A₆ = 6.3666 × 10⁻⁶ A₈ = −6.2546 × 10⁻⁷ A₁₀ = 0 Fourteenth surface K= 0 A₂ = 0 A₄ = 2.9509 × 10⁻⁴ A₆ = 5.8599 × 10⁻⁵ A₈ = 3.9534 × 10⁻⁶ A₁₀= 0 Fifteenth surface K = 0 A₂ = 0 A₄ = 4.1434 × 10⁻³ A₆ = 1.3121 × 10⁻⁴A₈ = 4.6939 × 10⁻⁵ A₁₀ = 0 Eighteenth surface K = 0 A₂ = 0 A₄ = 1.8250 ×10⁻³ A₆ = 1.0823 × 10⁻⁴ A₈ = −2.0337 × 10⁻⁵ A₁₀ = 0

Zoom data When the distance D0 is ∞, Wide-angle Middle Telephoto f (mm)3.24880 5.63959 9.74406 Fno 2.7241 3.4516 4.8572 D0 ∞ ∞ ∞ D6 0.898003.28004 0.90004 D9 9.70505 4.27059 0.89565 D15 1.70893 4.75924 10.51630D20 1.00000 1.00000 1.00000

Second Embodiment

FIG. 6 shows an optical arrangement of the second embodiment of the zoomlens used in the electronic imaging device according to the presentinvention. FIGS. 7A, 7B, and 7C show optical arrangements at wide-angle,middle, and telephoto positions, respectively, in the second embodiment.

As shown in FIG. 6, the electronic imaging device of the secondembodiment has, in order from the object side, a zoom lens and a CCDwhich is an electronic image sensor. In this figure, again, referencesymbol I represents the imaging plane of the CCD. The plane-parallel CCDcover glass CG is interposed between the zoom lens and the imaging planeI.

The zoom lens comprises, in order from the object side, the first lensunit G1, the second lens unit G2 which is the first moving lens unit,the aperture stop S, the third lens unit G3 which is the second movinglens unit, and the fourth lens unit G4.

The first lens unit G1 includes, in order from the object side, thenegative meniscus lens L1 ₁ with a convex surface directed toward theobject side, the reflective optical component R1 having a reflectingsurface for bending the optical path, and the biconvex positive lens L1₂.

The reflective optical component R1 is constructed as a front surfacemirror bending the optical path by 90°. The reflecting surface of thefront surface mirror is designed to be deformable so that the profile ofthe reflecting surface is changed and thereby the focusing operation isperformed.

Also, the aspect ratio of the effective imaging area in each of theembodiments of the present invention is 3:4, and the optical path islaterally bent.

The second lens unit G2 includes, in order from the object side, thecemented lens with the biconcave negative lens L2 ₁ and the positivemeniscus lens L2 ₂ with a convex surface directed toward the objectside, having negative refracting power as a whole.

The third lens unit G3 includes, in order from the object side, thecemented lens with the biconvex positive lens L3 ₁ and the biconcavenegative lens L3 ₂, and the positive meniscus lens L3 ₃ with a convexsurface directed toward the object side, having positive refractingpower as a whole.

The fourth lens unit G4 includes, in order from the object side, acemented lens with a biconcave negative lens L4 ₁′ and a biconvexpositive lens L4 ₂.

When the magnification of the zoom lens is changed, extending from thewide-angle position to the telephoto position, the first lens unit G1and the fourth lens unit G4 remain fixed; the second lens unit G2 ismoved back and forth on the image side to follow a convex path (that is,after being moved toward the image side to widen once spacing betweenthe first lens unit G1 and the second lens unit G2, narrows the spacingwhile moving toward the object side); and the third lens unit G3 ismoved toward the object side only, together with the aperture stop S.

The first lens unit G1 and the fourth lens unit G4 remain fixed evenwhen the focusing operation is performed.

Aspherical surfaces are provided to the image-side surface of thenegative meniscus lens L1 ₁ with a convex surface directed toward theobject side in the first lens unit G1, both surfaces of the positivemeniscus lens L3 ₃ with a convex surface directed toward the object sidein the third lens unit G3, and the image-side surface of the biconvexpositive lens L4 ₂ in the fourth lens unit G4.

Subsequently, numerical data of optical members constituting the zoomlens of the second embodiment are shown below.

Numerical data 2 r₁ = 74.4969 d₁ = 0.7000 n_(d1) = 1.80610 ν_(d1) =40.92 r₂ = 6.3385 (aspherical) d₂ = 1.7000 r₃ = ∞ d₃ = 6.8000 r₄ = ∞ d₄= 0.1500 r₅ = 12.2080 d₅ = 1.5500 n_(d5) = 1.72916 ν_(d5) = 54.68 r₆ =−169.5645 d₆ = D6 r₇ = −9.7882 d₇ = 0.7000 n_(d7) = 1.72916 ν_(d7) =54.68 r₈ = 8.0000 d₈ = 1.3500 n_(d8) = 1.84666 ν_(d8) = 23.78 r₉ =27.1517 d₉ = D9 r₁₀ = ∞ (stop) d₁₀ = 0 r₁₁ = 4.9532 d₁₁ = 3.0000 n_(d11)= 1.72916 ν_(d11) = 54.68 r₁₂ = −9.0000 d₁₂ = 0.7000 n_(d12) = 1.84666ν_(d12) = 23.78 r₁₃ = 24.5762 d₁₃ = 0.3000 r₁₄ = 10.0773 (aspherical)d₁₄ = 1.0000 n_(d14) = 1.69350 ν_(d14) = 53.21 r₁₅ = 12.2161(aspherical) d₁₅ = D15 r₁₆ = ∞ (position of d₁₆ = 4.0000 variabletransmittance means or shutter) r₁₇ = −44.4371 d₁₇ = 0.7000 n_(d17) =1.80518 ν_(d17) = 25.42 r₁₈ = 20.0000 d₁₈ = 1.2000 n_(d18) = 1.58313ν_(d18) = 59.38 r₁₉ = −10.5475 (aspherical) d₁₉ = 0.7000 r₂₀ = ∞ d₂₀ =0.6000 n_(d20) = 1.51633 ν_(d20) = 64.14 r₂₁ = ∞ d₂₁ = D21 r₂₂ = ∞(imaging plane) d₂₂ = 0 Aspherical coefficients Second surface K = 0 A₂= 0 A₄ = −6.0504 × 10⁻⁴ A₆ = 4.3029 × 10⁻⁶ A₈ = −5.2183 × 10⁻⁷ A₁₀ = 0Fourteenth surface K = 0 A₂ = 0 A₄ = 6.6247 × 10⁻⁴ A₆ = −2.9526 × 10⁻⁵A₈ = 3.3686 × 10⁻⁶ A₁₀ = 0 Fifteenth surface K = 0 A₂ = 0 A₄ = 4.3514 ×10⁻³ A₆ = 2.7664 × 10⁻⁵ A₈ = 4.2826 × 10⁻⁵ A₁₀ = 0 Nineteenth surface K= 0 A₂ = 0 A₄ = 9.6272 × 10⁻⁴ A₆ = 2.3883 × 10⁻⁴ A₈ = −3.0856 × 10^(−5*)A₁₀ = 0

Zoom data When the distance D0 is ∞, Wide-angle Middle Telephoto f (mm)3.25205 5.63896 9.74755 Fno 2.7329 3.4864 4.8975 D0 ∞ ∞ ∞ D6 0.898773.34248 0.90062 D9 9.99049 4.32715 0.89789 D15 1.78776 5.00483 10.87853D21 1.00000 1.00000 1.00000

Third Embodiment

FIG. 8 shows an optical arrangement of the third embodiment of the zoomlens used in the electronic imaging device according to the presentinvention. FIGS. 9A, 9B, and 9C show optical arrangements at wide-angle,middle, and telephoto positions, respectively, in the third embodiment.FIGS. 10A-10D show aberration characteristics at the wide-angle positionin the third embodiment. FIGS. 11A-11D show aberration characteristicsat the middle position in the third embodiment. FIGS. 12A-12D showaberration characteristics at the telephoto position in the thirdembodiment.

As shown in FIG. 8, the electronic imaging device of the thirdembodiment has, in order from the object side, a zoom lens and a CCDwhich is an electronic image sensor. In this figure, again, referencesymbol I represents the imaging plane of the CCD. The plane-parallel CCDcover glass CG is interposed between the zoom lens and the imaging planeI.

The zoom lens comprises, in order from the object side, the first lensunit G1, the second lens unit G2 which is the first moving lens unit,the aperture stop S, the third lens unit G3 which is the second movinglens unit, and the fourth lens unit G4.

The first lens unit G1 includes, in order from the object side, thenegative meniscus lens L1 ₁ with a convex surface directed toward theobject side, the reflective optical component R1 having a reflectingsurface for bending the optical path, and the biconvex positive lens L1₂.

The reflective optical component R1 is constructed as a front surfacemirror bending the optical path by 90°. The reflecting surface of thefront surface mirror is designed to be deformable so that the profile ofthe reflecting surface is changed and thereby the focusing operation isperformed.

Also, the aspect ratio of the effective imaging area in each of theembodiments of the present invention is 3:4, and the optical path islaterally bent.

The second lens unit G2 includes, in order from the object side, thecemented lens with the biconcave negative lens L2 ₁ and the positivemeniscus lens L2 ₂ with a convex surface directed toward the objectside, having negative refracting power as a whole.

The third lens unit G3 includes, in order from the object side, acemented lens with the biconvex positive lens L3 ₁, the biconcavenegative lens L3 ₂, and the positive meniscus lens L3 ₃ with a convexsurface directed toward the object side, having positive refractingpower as a whole.

The fourth lens unit G4 includes, in order from the object side, acemented lens with a negative meniscus lens L4 ₁″ with a convex surfacedirected toward the object side and the biconvex positive lens L4 ₂.

When the magnification of the zoom lens is changed, extending from thewide-angle position to the telephoto position, the first lens unit G1and the fourth lens unit G4 remain fixed; the second lens unit G2 ismoved back and forth on the image side to follow a convex path (that is,after being moved toward the image side to widen once spacing betweenthe first lens unit G1 and the second lens unit G2, narrows the spacingwhile moving toward the object side); and the third lens unit G3 ismoved toward the object side only, together with the aperture stop S.

The first lens unit G1 and the fourth lens unit G4 remain fixed evenwhen the focusing operation is performed.

Aspherical surfaces are provided to the image-side surface of thenegative meniscus lens L1 ₁ with a convex surface directed toward theobject side in the first lens unit G1, the object-side surface of thebiconvex positive lens L3 ₁ and the image-side surface of the positivemeniscus lens L3 ₃ with a convex surface directed toward the object sidein the third lens unit G3, and the image-side surface of the biconvexpositive lens L4 ₂ in the fourth lens unit G4.

Subsequently, numerical data of optical members constituting the zoomlens of the third embodiment are shown below.

Numerical data 3 r₁ = 59.7815 d₁ = 0.7000 n_(d1) = 1.80610 ν_(d1) =40.92 r₂ = 6.0756 (aspherical) d₂ = 1.7000 r₃ = ∞ d₃ = 6.8000 r₄ = ∞ d₄= 0.1500 r₅ = 11.7992 d₅ = 1.5500 n_(d5) = 1.72916 ν_(d5) = 54.68 r₆ =−179.5914 d₆ = D6 r₇ = −11.1399 d₇ = 0.7000 n_(d7) = 1.72916 ν_(d7) =54.68 r₈ = 8.0000 d₈ = 1.3500 n_(d8) = 1.84666 ν_(d8) = 23.78 r₉ =22.5506 d₉ = D9 r₁₀ = ∞ (stop) d₁₀ = 0 r₁₁ = 4.4541 (aspherical) d₁₁ =2.6000 n_(d11) = 1.74320 ν_(d11) = 49.34 r₁₂ = −36.5357 d₁₂ = 0.7000n_(d12) = 1.84666 ν_(d12) = 23.78 r₁₃ = 5.8033 d₁₃ = 1.0000 n_(d13) =1.69350 ν_(d13) = 53.21 r₁₄ = 20.1908 (aspherical) d₁₄ = D14 r₁₅ = ∞(position of d₁₅ = 3.9000 variable transmittance means or shutter) r₁₆ =114.5613 d₁₆ = 0.7000 n_(d16) = 1.84666 ν_(d16) = 23.78 r₁₇ = 15.0000d₁₇ = 1.4000 n_(d17) = 1.58313 ν_(d17) = 59.38 r₁₈ = −13.0230(aspherical) d₁₈ = 0.7000 r₁₉ = ∞ d₁₉ = 0.6000 n_(d19) = 1.51633 ν_(d19)= 64.14 r₂₀ = ∞ d₂₀ = D20 r₂₁ = ∞ (imaging plane) d₂₁ = 0 Asphericalcoefficients Second surface K = 0 A₂ = 0 A₄ = −5.8861 × 10⁻⁴ A₆ = 2.2837× 10⁻⁶ A₈ = −5.4903 × 10⁻⁷ A₁₀ = 0 Eleventh surface K = 0 A₂ = 0 A₄ =7.8543 × 10⁻⁵ A₆ = 1.1512 × 10⁻⁵ A₈ = 1.2754 × 10⁻⁶ A₁₀ = 0 Fourteenthsurface K = 0 A₂ = 0 A₄ = 4.7308 × 10⁻³ A₆ = 1.0524 × 10⁻⁴ A₈ = 7.9868 ×10⁻⁵ A₁₀ = 0 Eighteenth surface K = 0 A₂ = 0 A₄ = 5.4330 × 10⁻⁴ A₆ =3.5735 × 10⁻⁴ A₈ = −4.3307 × 10⁻⁵ A₁₀ = 0

Zoom data When the distance D0 is ∞, Wide-angle Middle Telephoto f (mm)3.25322 5.63788 9.74711 Fno 2.6846 3.4315 4.8540 D0 ∞ ∞ ∞ D6 0.898973.36572 0.90042 D9 10.05921 4.38120 0.89765 D14 1.97939 5.18949 11.14311D20 1.00000 1.00000 1.00000

Fourth Embodiment

FIG. 13 shows an optical arrangement of the fourth embodiment of thezoom lens used in the electronic imaging device according to the presentinvention. FIGS. 14A, 14B, and 14C show optical arrangements atwide-angle, middle, and telephoto positions, respectively, in the fourthembodiment. FIGS. 15A-15D show aberration characteristics at thewide-angle position in the fourth embodiment. FIGS. 16A-16D showaberration characteristics at the middle position in the fourthembodiment. FIGS. 17A-17D show aberration characteristics at thetelephoto position in the fourth embodiment.

As shown in FIG. 13, the electronic imaging device of the fourthembodiment has, in order from the object side, a zoom lens and a CCDwhich is an electronic image sensor. In this figure, again, referencesymbol I represents the imaging plane of the CCD. The plane-parallel CCDcover glass CG is interposed between the zoom lens and the imaging planeI.

The zoom lens comprises, in order from the object side, the first lensunit G1, the second lens unit G2 which is the first moving lens unit,the aperture stop S, the third lens unit G3 which is the second movinglens unit, and the fourth lens unit G4.

The first lens unit G1 includes, in order from the object side, thenegative meniscus lens L1 ₁ with a convex surface directed toward theobject side, the reflective optical component R1 having a reflectingsurface for bending the optical path, and the biconvex positive lens L1₂.

The reflective optical component R1 is constructed as a front surfacemirror bending the optical path by 90°. The reflecting surface of thefront surface mirror is designed to be deformable so that the profile ofthe reflecting surface is changed and thereby the focusing operation isperformed.

Also, the aspect ratio of the effective imaging area in each of theembodiments of the present invention is 3:4, and the optical path islaterally bent.

The second lens unit G2 includes, in order from the object side, thecemented lens with the biconcave negative lens L2 ₁ and the positivemeniscus lens L2 ₂ with a convex surface directed toward the objectside, having negative refracting power as a whole.

The third lens unit G3 includes, in order from the object side, thebiconvex positive lens L3 ₁ and a cemented lens with a biconvex positivelens L3 ₂′ and a biconcave negative lens L3 ₃′, having positiverefracting power as a whole.

The fourth lens unit G4 includes a positive meniscus lens L4 ₁ ′″ with aconvex surface directed toward the object side.

When the magnification of the zoom lens is changed, extending from thewide-angle position to the telephoto position, the first lens unit G1and the fourth lens unit G4 remain fixed; the second lens unit G2 ismoved back and forth on the image side to follow a convex path (that is,after being moved toward the image side to widen once spacing betweenthe first lens unit G1 and the second lens unit G2, narrows the spacingwhile moving toward the object side); and the third lens unit G3 ismoved toward the object side only, together with the aperture stop S.

The first lens unit G1 and the fourth lens unit G4 remain fixed evenwhen the focusing operation is performed.

Aspherical surfaces are provided to the image-side surface of thenegative meniscus lens L1 ₁ with a convex surface directed toward theobject side in the first lens unit G1, the object-side surface of thebiconvex positive lens L3 ₁ in the third lens unit G3, and theobject-side surface of the positive meniscus lens L4 ₁′″ with a convexsurface directed toward the object side, constituting the fourth lensunit G4.

Subsequently, numerical data of optical members constituting the zoomlens of the fourth embodiment are shown below.

Numerical data 4 r₁ = 52.2760 d₁ = 0.7000 n_(d1) = 1.80610 ν_(d1) =40.92 r₂ = 5.7580 (aspherical) d₂ = 1.7000 r₃ = ∞ d₃ = 6.8000 r₄ = ∞ d₄= 0.1500 r₅ = 16.0001 d₅ = 1.5500 n_(d5) = 1.72916 ν_(d5) = 54.68 r₆ =−30.1872 d₆ = D6 r₇ = −14.5275 d₇ = 0.7000 n_(d7) = 1.72916 ν_(d7) =54.68 r₈ = 8.5000 d₈ = 1.3500 n_(d8) = 1.84666 ν_(d8) = 23.78 r₉ =22.8461 d₉ = D9 r₁₀ = ∞ (stop) d₁₀ = 0 r₁₁ = 6.7921 (aspherical) d₁₁ =2.0000 n_(d11) = 1.74320 ν_(d11) = 49.34 r₁₂ = −17.1573 d₁₂ = 0.1500 r₁₃= 6.6023 d₁₃ = 2.0000 n_(d13) = 1.69680 ν_(d13) = 55.53 r₁₄ = −12.0000d₁₄ = 0.7000 n_(d14) = 1.80518 ν_(d14) = 25.42 r₁₅ = 3.4303 d₁₅ = 2.5000r₁₆ = ∞ (position of d₁₆ = D16 variable transmittance means or shutter)r₁₇ = 5.2486 (aspherical) d₁₇ = 1.3000 n_(d17) = 1.58313 ν_(d17) = 59.38r₁₈ = 14.6752 d₁₈ = 0.7000 r₁₉ = ∞ d₁₉ = 0.6000 n_(d19) = 1.51633ν_(d19) = 64.14 r₂₀ = ∞ d₂₀ = D20 r₂₁ = ∞ (imaging surface) d₂₁ = 0Aspherical coefficients Second surface K = 0 A₂ = 0 A₄ = −7.5842 × 10⁻⁴A₆ = 1.7230 × 10⁻⁵ A₈ = −1.0788 × 10⁻⁶ A₁₀ = 0 Eleventh surface K = 0 A₂= 0 A₄ = −6.3767 × 10⁻⁴ A₆ = −3.2039 × 10⁻⁶ A₈ = −1.8591 × 10⁻⁷ A₁₀ = 0Seventeenth surface K = 0 A₂ = 0 A₄ = −9.5208 × 10⁻⁴ A₆ = 1.7318 × 10⁻⁴A₈ = −1.2845 × 10⁻⁵ A₁₀ = 0

Zoom data When the distance D0 is ∞, Wide-angle Middle Telephoto f (mm)3.24494 5.63626 9.75588 Fno 2.5243 3.3051 4.8453 D0 ∞ ∞ ∞ D6 0.899683.58051 0.90275 D9 10.64759 4.65512 0.90377 D16 2.44627 5.75714 12.18681D20 1.00000 1.00000 1.00000

Fifth Embodiment

FIG. 18 shows an optical arrangement of the fifth embodiment of the zoomlens used in the electronic imaging device according to the presentinvention. FIGS. 19A, 19B, and 19C show optical arrangements atwide-angle, middle, and telephoto positions, respectively, in the fifthembodiment.

As shown in FIG. 18, the electronic imaging device of the fifthembodiment has, in order from the object side, a zoom lens and a CCDwhich is an electronic image sensor. In this figure, again, referencesymbol I represents the imaging plane of the CCD. The plane-parallel CCDcover glass CG is interposed between the zoom lens and the imaging planeI.

The zoom lens comprises, in order from the object side, the first lensunit G1, the second lens unit G2 which is the first moving lens unit,the aperture stop S, the third lens unit G3 which is the second movinglens unit, and the fourth lens unit G4.

The first lens unit G1 includes, in order from the object side, thenegative meniscus lens L1 ₁ with a convex surface directed toward theobject side, the reflective optical component R1 having a reflectingsurface for bending the optical path, and the biconvex positive lens L1₂.

The reflective optical component R1 is constructed as a front surfacemirror bending the optical path by 90°. The reflecting surface of thefront surface mirror is designed to be deformable so that the profile ofthe reflecting surface is changed and thereby the focusing operation isperformed.

Also, the aspect ratio of the effective imaging area in each of theembodiments of the present invention is 3:4, and the optical path islaterally bent.

The second lens unit G2 includes, in order from the object side, thecemented lens with the biconcave negative lens L2 ₁ and the positivemeniscus lens L2 ₂ with a convex surface directed toward the objectside, having negative refracting power as a whole.

The third lens unit G3 includes, in order from the object side, thebiconvex positive lens L3 ₁ and the cemented lens with the biconvexpositive lens L3 ₂′ and the biconcave negative lens L3 ₃′, havingpositive refracting power as a whole.

The fourth lens unit G4 includes the positive meniscus lens L4 ₁ with aconcave surface directed toward the object side.

When the magnification of the zoom lens is changed, extending from thewide-angle position to the telephoto position, the first lens unit G1and the fourth lens unit G4 remain fixed; the second lens unit G2 ismoved back and forth on the image side to follow a convex path (that is,after being moved toward the image side to widen once spacing betweenthe first lens unit G1 and the second lens unit G2, narrows the spacingwhile moving toward the object side); and the third lens unit G3 ismoved toward the object side only, together with the aperture stop S.

The first lens unit G1 and the fourth lens unit G4 remain fixed evenwhen the focusing operation is performed.

Aspherical surfaces are provided to the image-side surface of thenegative meniscus lens L1 ₁ with a convex surface directed toward theobject side in the first lens unit G1, the object-side surface of thebiconvex positive lens L3 ₁ in the third lens unit G3, and theimage-side surface of the positive meniscus lens L4 ₁ with a concavesurface directed toward the object side, constituting the fourth lensunit G4.

Subsequently, numerical data of optical members constituting the zoomlens of the fifth embodiment are shown below.

Numerical data 5 r₁ = 102.2644 d₁ = 0.7000 n_(d1) = 1.80610 ν_(d1) =40.92 r₂ = 6.4583 (aspherical) d₂ = 1.7000 r₃ = ∞ d₃ = 6.8000 r₄ = ∞ d₄= 0.1500 r₅ = 11.8116 d₅ = 1.6000 n_(d5) = 1.72916 ν_(d5) = 54.68 r₆ =−211.6601 d₆ = D6 r₇ = −9.9617 d₇ = 0.7000 n_(d7) = 1.72916 ν_(d7) =54.68 r₈ = 9.5000 d₈ = 1.3000 n_(d8) = 1.84666 ν_(d8) = 23.78 r₉ =41.0310 d₉ = D9 r₁₀ = ∞ (stop) d₁₀ = 0 r₁₁ = 7.0537 (aspherical) d₁₁ =1.7000 n_(d11) = 1.74320 ν_(d11) = 49.34 r₁₂ = −15.1973 d₁₂ = 0.1500 r₁₃= 4.7737 d₁₃ = 2.1000 n_(d13) = 1.74320 ν_(d13) = 49.34 r₁₄ = −17.0000d₁₄ = 0.7000 n_(d14) = 1.84666 ν_(d14) = 23.78 r₁₅ = 2.5724 d₁₅ = 1.7000r₁₆ = ∞ (position of d₁₆ = D16 variable transmittance means or shutter)r₁₇ = −34.4280 d₁₇ = 1.7000 n_(d17) = 1.57099 ν_(d17) = 50.80 r₁₈ =−5.8134 (aspherical) d₁₈ = 0.7000 r₁₉ = ∞ d₁₉ = 0.6000 n_(d19) = 1.51633ν_(d19) = 64.14 r₂₀ = ∞ d₂₀ = D20 r₂₁ = ∞ (imaging plane) d₂₁ = 0Aspherical coefficients Second surface K = 0 A₂ = 0 A₄ = −5.0036 × 10⁻⁴A₆ = 3.1904 × 10⁻⁶ A₈ = −4.2907 × 10⁻⁷ A₁₀ = 0 Eleventh surface K = 0 A₂= 0 A₄ = −6.6405 × 10⁻⁴ A₆ = −7.9814 × 10⁻⁷ A₈ = −1.7621 × 10⁻⁷ A₁₀ = 0Eighteenth surface K = 0 A₂ = 0 A₄ = 2.0836 × 10⁻³ A₆ = 8.7260 × 10⁻⁵ A₈= −1.9733 × 10⁻⁵ A₁₀ = 0

Zoom data When the distance D0 is ∞, Wide-angle Middle Telephoto f (mm)3.25606 5.63818 9.75165 Fno 2.7198 3.6329 5.3468 D0 ∞ ∞ ∞ D6 0.900083.07797 0.90116 D9 8.98407 3.96139 0.90291 D16 1.81805 4.66415 9.89808D20 1.00000 1.00000 1.00000

Sixth Embodiment

FIG. 20 shows an optical arrangement of the sixth embodiment of the zoomlens used in the electronic imaging device according to the presentinvention. FIGS. 21A, 21B, and 21C show optical arrangements atwide-angle, middle, and telephoto positions, respectively, in the sixthembodiment.

As shown in FIG. 20, the electronic imaging device of the sixthembodiment has, in order from the object side, a zoom lens and a CCDwhich is an electronic image sensor. In this figure, again, referencesymbol I represents the imaging plane of the CCD. The plane-parallel CCDcover glass CG is interposed between the zoom lens and the imaging planeI.

The zoom lens comprises, in order from the object side, the first lensunit G1, the second lens unit G2 which is the first moving lens unit,the aperture stop S, the third lens unit G3 which is the second movinglens unit, and the fourth lens unit G4.

The first lens unit G1 includes, in order from the object side, thenegative meniscus lens L1 ₁ with a convex surface directed toward theobject side, the reflective optical component R1 having a reflectingsurface for bending the optical path, and the biconvex positive lens L1₂.

The reflective optical component R1 is constructed as a front surfacemirror bending the optical path by 90°. The reflecting surface of thefront surface mirror is designed to be deformable so that the profile ofthe reflecting surface is changed and thereby the focusing operation isperformed.

Also, the aspect ratio of the effective imaging area in each of theembodiments of the present invention is 3:4, and the optical path islaterally bent.

The second lens unit G2 includes, in order from the object side, thecemented lens with the biconcave negative lens L2 ₁ and the positivemeniscus lens L2 ₂ with a convex surface directed toward the objectside, having negative refracting power as a whole.

The third lens unit G3 includes, in order from the object side, thebiconvex positive lens L3 ₁ and the cemented lens with the biconvexpositive lens L3 ₂′ and the biconcave negative lens L3 ₃′, havingpositive refracting power as a whole.

The fourth lens unit G4 includes the biconvex positive lens L4 ₁″″.

When the magnification of the zoom lens is changed, extending from thewide-angle position to the telephoto position, the first lens unit G1and the fourth lens unit G4 remain fixed; the second lens unit G2 ismoved back and forth on the image side to follow a convex path (that is,after being moved toward the image side to widen once spacing betweenthe first lens unit G1 and the second lens unit G2, narrows the spacingwhile moving toward the object side); and the third lens unit G3 ismoved toward the object side only, together with the aperture stop S.

The first lens unit G1 and the fourth lens unit G4 remain fixed evenwhen the focusing operation is performed.

Aspherical surfaces are provided to the image-side surface of thenegative meniscus lens L1 ₁ with a convex surface directed toward theobject side in the first lens unit G1, both surfaces of the biconvexpositive lens L3 ₁ in the third lens unit G3, and the image-side surfaceof the biconvex positive lens L4 ₁″″ constituting the fourth lens unitG4.

Subsequently, numerical data of optical members constituting the zoomlens of the sixth embodiment are shown below.

Numerical data 6 r₁ = 287.7208 d₁ = 0.9000 n_(d1) = 1.80610 ν_(d1) =40.92 r₂ = 8.5536 (aspherical) d₂ = 2.1000 r₃ = ∞ d₃ = 8.4000 r₄ = ∞ d₄= 0.1500 r₅ = 16.2840 d₅ = 1.7000 n_(d5) = 1.73400 ν_(d5) = 51.47 r₆ =−87.4861 d₆ = D6 r₇ = −12.9420 d₇ = 0.7000 n_(d7) = 1.72916 ν_(d7) =54.68 r₈ = 11.5000 d₈ = 1.3500 n_(d8) = 1.84666 ν_(d8) = 23.78 r₉ =47.4193 d₉ = D9 r₁₀ = ∞ (stop) d₁₀ = 0 r₁₁ = 8.0948 (aspherical) d₁₁ =1.9000 n_(d11) = 1.74320 ν_(d11) = 49.34 r₁₂ = −18.2182 (aspherical) d₁₂= 0.1500 r₁₃ = 6.1759 d₁₃ = 2.5000 n_(d13) = 1.74320 ν_(d13) = 49.34 r₁₄= −20.0000 d₁₄ = 0.7000 n_(d14) = 1.84666 ν_(d14) = 23.78 r₁₅ = 3.1875d₁₅ = D15 r₁₆ = ∞ (position of d₁₆ = 3.6250 variable transmittance meansor shutter) r₁₇ = 15.0796 d₁₇ = 1.8000 n_(d17) = 1.57099 ν_(d17) = 50.80r₁₈ = −14.9993 (aspherical) d₁₈ = 0.8750 r₁₉ = ∞ d₁₉ = 0.7500 n_(d19) =1.51633 ν_(d19) = 64.14 r₂₀ = ∞ d₂₀ = D20 r₂₁ = ∞ (imaging plane) d₂₁ =0 Aspherical coefficients Second surface K = 0 A₂ = 0 A₄ = −2.9216 ×10⁻⁴ A₆ = 2.7058 × 10⁻⁶ A₈ = −1.0174 × 10⁻⁷ A₁₀ = 0 Eleventh surface K =0 A₂ = 0 A₄ = −5.4278 × 10⁻⁴ A₆ = −4.6715 × 10⁻⁵ A₈ = −4.4895 × 10⁻⁷ A₁₀= 0 Twelfth surface K = 0 A₂ = 0 A₄ = −1.6294 × 10⁻⁴ A₆ = −5.7124 × 10⁻⁵A₈ = 7.4143 × 10⁻⁷ A₁₀ = 0 Eighteen surface K = 0 A₂ = 0 A₄ = 5.3686 ×10⁻⁴ A₆ = 7.2927 × 10⁻⁶ A₈ = −2.1769 × 10⁻⁶ A₁₀ = 0

Zoom data When the distance D0 is ∞, Wide-angle Middle Telephoto f (mm)4.00038 6.92729 12.00247 Fno 2.5763 3.4177 5.0414 D0 ∞ ∞ ∞ D6 0.899753.74456 0.90123 D9 11.36100 4.89989 0.90214 D15 1.36578 4.98133 11.82310D20 1.00000 1.00000 1.00000

Seventh Embodiment

FIG. 22 shows an optical arrangement of the seventh embodiment of thezoom lens used in the electronic imaging device according to the presentinvention. FIGS. 23A, 23B, and 23C show optical arrangements atwide-angle, middle, and telephoto positions, respectively, in theseventh embodiment.

As shown in FIG. 22, the electronic imaging device of the seventhembodiment has, in order from the object side, a zoom lens and a CCDwhich is an electronic image sensor. In this figure, again, referencesymbol I represents the imaging plane of the CCD. The plane-parallel CCDcover glass CG is interposed between the zoom lens and the imaging planeI.

The zoom lens comprises, in order from the object side, the first lensunit G1, the second lens unit G2 which is the first moving lens unit,the aperture stop S, the third lens unit G3 which is the second movinglens unit, and the fourth lens unit G4.

The first lens unit G1 includes, in order from the object side, thenegative meniscus lens L1 ₁ with a convex surface directed toward theobject side, the reflective optical component R1 having a reflectingsurface for bending the optical path, and a positive meniscus lens L1 ₂′with a convex surface directed toward the object side.

The reflective optical component R1 is constructed as a front surfacemirror bending the optical path by 90°. The reflecting surface of thefront surface mirror is designed to be deformable so that the profile ofthe reflecting surface is changed and thereby the focusing operation isperformed.

Also, the aspect ratio of the effective imaging area in each of theembodiments of the present invention is 3:4, and the optical path islaterally bent.

The second lens unit G2 includes, in order from the object side, thecemented lens with the biconcave negative lens L2 ₁ and the positivemeniscus lens L2 ₂ with a convex surface directed toward the objectside, having negative refracting power as a whole.

The third lens unit G3 includes, in order from the object side, thebiconvex positive lens L3 ₁ and the cemented lens with the biconvexpositive lens L3 ₂′ and the biconcave negative lens L3 ₃′, havingpositive refracting power as a whole.

The fourth lens unit G4 includes the positive meniscus lens L4 ₁ with aconcave surface directed toward the object side.

When the magnification of the zoom lens is changed, extending from thewide-angle position to the telephoto position, the first lens unit G1and the fourth lens unit G4 remain fixed; the second lens unit G2 ismoved back and forth on the image side to follow a convex path (that is,after being moved toward the image side to widen once spacing betweenthe first lens unit G1 and the second lens unit G2, narrows the spacingwhile moving toward the object side); and the third lens unit G3 ismoved toward the object side only, together with the aperture stop S.

The first lens unit G1 and the fourth lens unit G4 remain fixed evenwhen the focusing operation is performed.

Aspherical surfaces are provided to the image-side surface of thenegative meniscus lens L1 ₁ with a convex surface directed toward theobject side in the first lens unit G1, both surfaces of the biconvexpositive lens L3 ₁ in the third lens unit G3, and the image-side surfaceof the positive meniscus lens L4 ₁ with a concave surface directedtoward the object side, constituting the fourth lens unit G4.

Subsequently, numerical data of optical members constituting the zoomlens of the seventh embodiment are shown below.

Numerical data 7 r₁ = 179.9734 d₁ = 0.9000 n_(d1) = 1.80610 ν_(d1) =40.92 r₂ = 8.7645 (aspherical) d₂ = 1.8000 r₃ = ∞ d₃ = 8.4000 r₄ = ∞ d₄= 0.1500 r₅ = 12.7792 d₅ = 1.7000 n_(d5) = 1.73400 ν_(d5) = 51.47 r₆ =112.8775 d₆ = D6 r₇ = −10.6752 d₇ = 0.7000 n_(d7) = 1.72916 ν_(d7) =54.68 r₈ = 11.0000 d₈ = 1.3500 n_(d8) = 1.84666 ν_(d8) = 23.78 r₉ =57.4122 d₉ = D9 r₁₀ = ∞ (stop) d₁₀ = 0 r₁₁ = 7.5375 (aspherical) d₁₁ =2.1000 n_(d11) = 1.74320 ν_(d11) = 49.34 r₁₂ = −14.2059 (aspherical) d₁₂= 0.1500 r₁₃ = 5.4153 d₁₃ = 2.1000 n_(d13) = 174300 ν_(d13) = 51.47 r₁₄= −25.0000 d₁₄ = 0.7000 n_(d14) = 1.84666 ν_(d14) = 23.78 r₁₅ = 2.8519d₁₅ = 1.6250 r₁₆ = ∞ (position of d₁₆ = D16 variable transmittance meansor shutter) r₁₇ = −13.9912 d₁₇ = 1.6000 n_(d17) = 1.68893 ν_(d17) =31.07 r₁₈ = −6.0274 (aspherical) d₁₈ = 0.8750 r₁₉ = ∞ d₁₉ = 0.7500n_(d19) = 1.51633 ν₁₉ = 64.14 r₂₀ = ∞ d₂₀ = D20 r₂₁ = ∞ (imaging plane)d₂₁ = 0 Aspherical coefficients Second surface K = 0 A₂ = 0 A₄ = −2.6082× 10⁻⁴ A₆ = 2.1812 × 10⁻⁶ A₈ = −9.2869 × 10⁻⁸ A₁₀ = 0 Eleventh surface K= 0 A₂ = 0 A₄ = −4.8935 × 10⁻⁴ A₆ = 8.2602 × 10⁻⁵ A₈ = −1.6349 × 10⁻⁶A₁₀ = 0 Twelfth surface K = 0 A₂ = 0 A₄ = 1.4604 × 10⁻⁴ A₆ = −1.1504 ×10⁻⁴ A₈ = 1.4427 × 10⁻⁶ A₁₀ = 0 Eighteenth surface K = 0 A₂ = 0 A₄ =1.6159 × 10⁻³ A₆ = −3.5024 × 10⁻⁵ A₈ = −2.8372 × 10⁻⁷ A₁₀ = 0

Zoom data When the distance D0 is ∞, Wide-angle Middle Telephoto f (mm)4.00059 6.92436 12.00132 Fno 2.5241 3.3645 4.9430 D0 ∞ ∞ ∞ D6 0.899713.35716 0.90160 D9 10.02202 4.33848 0.90196 D16 2.97093 6.19241 12.08905D20 1.00000 1.00000 1.00000

Subsequently, the values of parameters of the conditions in the first toseventh embodiments are listed in Tables 1 and 2.

TABLE 1 1st embodiment 2nd embodiment 3rd embodiment Lens data Numericaldata 1 Numerical data 2 Numerical data 3 Type of the third lens unit B BC Half field angle 33.0° 33.0° 33.0° at wide-angle position Half fieldangle 19.3° 19.3° 19.3° at middle position Half field angle 11.4° 11.4°11.4° at telephoto position L 4.0 4.0 4.0 a 1.85 1.85 2.0 f11/{squareroot over ((fw · fT))} −1.53101 −1.52589 −1.49860 f12/{square root over((fw · fT))} 2.65560 2.78401 2.70575 d/L 2.16250 2.16250 2.16250 ν1N40.92 40.92 40.92 {square root over ((fw · fT))}/f1 0.10554 0.066590.08163 βRw −0.58149 −0.56103 −0.53898 fRw/{square root over ((fw ·fT))} 1.52856 1.54866 1.54772 R_(C3)/R_(C1) 2.47814 4.96168 — L/R_(C2)−0.5 −0.44444 — ν_(CP) − ν_(CN) 25.56 30.90 — (R_(CF) + R_(CR))/(R_(CF)− R_(CR)) — — −1.56608 D_(C)/fw — — 1.32177 Σ{(1/Rci) − (1/Rca)}² — —0.01994 Σ{(1/vcj + 1) − (1/vcj)}² — — 1.0155 × 10⁻³ Σ{ncj + 1 − ncj}² —— 0.03416 (R_(IPF) + R_(IPR))/(R_(IPF) − R_(IPR)) −0.70009 −0.86568−0.87670 (R_(2F) + R_(2R))/(R_(2F) − R_(2R)) −0.34010 −0.47005 −0.33869fT/fw 2.99928 2.99736 2.99614 τ400/τ550 0.0 0.0 0.0 τ440/τ550 1.06 1.061.06 τ600/τ550 1.0 1.0 1.0 τ700/τ550 0.04 0.04 0.04 Bending point 3.33.3 3.4 Minimum distance 160 mm 160 mm 160 mm for photography Radius ofcurvature R of reflecting −578 −576 −576 surface at minimum distance

TABLE 2 4th embodiment 5th embodiment 6th embodiment 7th embodiment Lensdata Numerical data 4 Numerical data 5 Numerical data 6 Numerical data 7Type of the third lens unit A A A A Half field angle 33.1° 33.0° 33.4°33.4° at wide-angle position Half field angle 19.3° 19.2° 19.5° 19.5° atmiddle position Half field angle 11.4° 11.4° 11.6° 11.6° at telephotoposition L 4.0 4.0 5.0 5.0 a 1.85 2.0 2.0 2.0 f11/{square root over ((fw· fT))} −1.43633 −1.52262 −1.58055 −1.65335 f12/{square root over ((fw ·fT))} 2.58556 2.73107 2.71813 2.81321 d/L 2.16250 2.16250 2.130002.07000 ν1N 40.92 40.92 40.92 40.92 {square root over ((fw · fT))}/f10.11728 0.07952 0.09765 0.06712 BRw −0.43339 −0.48720 −0.45061 −0.50793fRw/{square root over ((fw · fT))} 1.54825 1.46665 1.46393 1.39741R_(C3)/R_(C1) 0.51956 0.53887 0.51612 0.52663 L/R_(C2) −0.33333 −0.23529−0.25000 −0.20000 ν_(CP) − ν_(CN) 30.11 25.56 25.56 27.69 (R_(CF) +R_(CR))/(R_(CF) − R_(CR)) — — — — D_(C)/fw — — — — Σ{(1/Rci) − (1/Rca)}²— — — — Σ{(1/vcj + 1) − (1/vcj)}² — — — — Σ{ncj + 1 − ncj}² — — — —(R_(IPF) + R_(IPR))/(R_(IPF) − R_(IPR)) −0.30716 −0.89429 −0.68615−1.25533 (R_(2F) + R_(2R))/(R_(2F) − R_(2R)) −0.22258 −0.60929 −0.57118−0.68643 fT/fw 3.0065 2.99492 3.00033 2.99989 τ400/τ550 0.0 0.0 0.0 0.0τ440/τ550 1.06 1.06 1.06 1.06 τ600/τ550 1.0 1.0 1.0 1.0 τ700/τ550 0.040.04 0.04 0.04 Bending point 3.3 3.3 4.0 4.2 Minimum distance 160 mm 160mm 200 mm 200 mm for photography Radius of curvature R of reflecting−600 −577 −717 −670 surface at minimum distance

Eighth Embodiment

FIG. 24 shows an optical arrangement of the eighth embodiment of thezoom lens used in the electronic imaging device according to the presentinvention. FIGS. 25A, 25B, and 25C show optical arrangements atwide-angle, middle, and telephoto positions, respectively, in the eighthembodiment. FIGS. 26A-26D show aberration characteristics at thewide-angle position, in focusing of the infinite object point, of thezoom lens in the eighth embodiment. FIGS. 27A-27D show aberrationcharacteristics at the middle position, in focusing of the infiniteobject point, of the zoom lens in the eighth embodiment. FIGS. 28A-28Dshow aberration characteristics at the telephoto position, in focusingof the infinite object point, of the zoom lens in the eighth embodiment.FIGS. 29A-29D show aberration characteristics at the wide-angleposition, in focusing of the short-distance object point, of the zoomlens in the eighth embodiment. FIGS. 30A-30D show aberrationcharacteristics at the middle position, in focusing of theshort-distance object point, of the zoom lens in the eighth embodiment.FIGS. 31A-31D show aberration characteristics at the telephoto position,in focusing of the short-distance object point, of the zoom lens in theeighth embodiment.

As shown in FIG. 24, the electronic imaging device of the eighthembodiment has, in order from the object side, a zoom lens and a CCDwhich is an electronic image sensor. In this figure, again, referencesymbol I represents the imaging plane of the CCD. The plane-parallel CCDcover glass CG is interposed between the zoom lens and the imaging planeI.

The zoom lens comprises, in order from the object side, the first lensunit G1, the second lens unit G2 which is the first moving lens unit,the aperture stop S, the third lens unit G3 which is the second movinglens unit, the fourth lens unit G4, and a fifth lens unit G5.

The first lens unit G1 includes, in order from the object side, thenegative meniscus lens L1 ₁ with a convex surface directed toward theobject side, the reflective optical component R1 having a reflectingsurface for bending the optical path, and the biconvex positive lens L1₂, having positive refracting power as a whole.

The reflective optical component R1 is constructed as a reflecting prismbending the optical path by 90°.

The second lens unit G2 includes, in order from the object side, thecemented lens with the biconcave negative lens L2 ₁ and the positivemeniscus lens L2 ₂ with a convex surface directed toward the objectside, having negative refracting power as a whole.

The third lens unit G3 includes, in order from the object side, thecemented lens with the positive meniscus lens L3 ₁ with a convex surfacedirected toward the object side and the negative meniscus lens L3 ₂ witha convex surface directed toward the object side, and the biconvexpositive lens L3 ₃, having positive refracting power as a whole.

The fourth lens unit G4 includes the negative meniscus lens L4 ₁ with aconvex surface directed toward the object side.

The fifth lens unit G5 includes, in order from the object side, acemented lens with a biconvex positive lens L5 ₁ and a biconcavenegative lens L5 ₂.

When the magnification of the zoom lens is changed, extending from thewide-angle position to the telephoto position, in focusing of theinfinite object point, the first lens unit G1 and the fifth lens unit G5remain fixed; the second lens unit G2 is moved back and forth on theimage side to follow a convex path (that is, after being moved towardthe image side to widen once spacing between the first lens unit G1 andthe second lens unit G2, narrows the spacing while moving toward theobject side); and the third lens unit G3 is moved toward the object sideonly, together with the aperture stop S.

In focusing of the short-distance object point, the second lens unit G2is shifted to the object side, and the fourth lens unit G4 is movedalong the optical axis.

The first lens unit G1 and the fifth lens unit G5 remain fixed even whenthe focusing operation is performed.

Aspherical surfaces are provided to the image-side surface of thenegative meniscus lens L1 ₁ with a convex surface directed toward theobject side in the first lens unit G1, the object-side surface of thepositive meniscus lens L3 ₁ with a convex surface directed toward theobject side in the third lens unit G3, and the object-side surface ofthe biconvex positive lens L5 ₁ in the fifth lens unit G5.

Subsequently, numerical data of optical members constituting the zoomlens of the eighth embodiment are shown below.

Numerical data 8 r₁ = 27.7123 d₁ = 0.7000 n_(d1) = 1.80610 ν_(d1) =40.92 r₂ = 5.9116 (aspherical) d₂ = 1.7000 r₃ = ∞ d₃ = 6.8000 n_(d3) =1.80610 ν_(d3) = 40.92 r₄ = ∞ d₄ = 0.1500 r₅ = 11.2199 d₅ = 1.3000n_(d5) = 1.72916 ν_(d5) = 54.68 r₆ = −569.8906 d₆ = D6 r₇ = −8.0963 d₇ =0.7000 n_(d7) = 1.72916 ν_(d7) = 54.68 r₈ = 6.5000 d₈ = 1.3000 n_(d8) =1.84666 ν_(d8) = 23.78 r₉ = 24.9922 d₉ = D9 r₁₀ = ∞ (stop) d₁₀ = 0 r₁₁ =4.5958 (aspherical) d₁₁ = 1.8000 n_(d11) = 1.74320 ν_(d11) = 49.34 r₁₂ =20.0000 d₁₂ = 0.7000 n_(d12) = 1.84666 ν_(d12) = 23.78 r₁₃ = 4.4049 d₁₃= 0.3000 r₁₄ = 7.9947 d₁₄ = 1.6000 n_(d14) = 1.72916 ν_(d14) = 54.68 r₁₅= −10.0877 d₁₅ = D15 r₁₆ = 19.9833 d₁₆ = 0.7000 n_(d16) = 1.48749ν_(d16) = 70.23 r₁₇ = 6.0725 d₁₇ = D17 r₁₈ = 7.4083 (aspherical) d₁₈ =1.6000 n_(d18) = 1.74320 ν_(d18) = 49.34 r₁₉ = −12.0000 d₁₉ = 0.7000n_(d19) = 1.84666 ν_(d19) = 23.78 r₂₀ = 40.3531 d₂₀ = 0.7000 r₂₁ = ∞ d₂₁= 0.6000 n_(d21) = 1.51633 ν_(d21) = 64.14 r₂₂ = ∞ d₂₂ = D22 r₂₃ = ∞(imaging plane) d₂₃ = 0 Aspherical coefficients Second surface K = 0 A₂= 0 A₄ = −6.4155 × 10⁻⁴ A₆ = 2.5228 × 10⁻⁶ A₈ = −8.7694 × 10⁻⁷ A₁₀ = 0Eleventh surface K = 0 A₂ = 0 A₄ = −1.0160 × 10⁻³ A₆ = 4.6636 × 10⁻⁶ A₈= −1.0125 × 10⁻⁶ A₁₀ = 0 Eighteenth surface K = 0 A₂ = 0 A₄ = −9.6507 ×10⁻⁵ A₆ = −5.2496 × 10⁻⁵ A₈ = 4.9151 × 10⁻⁶ A₁₀ = 0

Zoom data Wide-angle Middle Telephoto When the distance D0 is ∞, f(mm)3.25089 5.63716 9.74797 Fno 2.6146 3.2986 4.4792 D0 ∞ ∞ ∞ D6 0.798692.93966 0.79967 D9 9.23582 3.96028 0.89698 D15 3.71237 6.47491 11.24992D17 1.81385 2.18422 2.61424 D22 1.00000 1.00000 1.00000 When thedistance D0 is short (16 cm), D0 162.6560 162.6560 162.6560 D6 0.798692.93966 0.79967 D9 9.23582 3.96028 0.89698 D15 3.86053 6.90038 12.50997D17 1.66569 1.75875 1.35418 D22 1.00000 1.00000 1.00000

Ninth Embodiment

FIG. 32 shows an optical arrangement of the ninth embodiment of the zoomlens used in the electronic imaging device according to the presentinvention. FIGS. 33A, 33B, and 33C show optical arrangements atwide-angle, middle, and telephoto positions, respectively, in the ninthembodiment. FIGS. 34A-34D show aberration characteristics at thewide-angle position, in focusing of the infinite object point, of thezoom lens in the ninth embodiment. FIGS. 35A-35D show aberrationcharacteristics at the middle position, in focusing of the infiniteobject point, of the zoom lens in the ninth embodiment. FIGS. 36A-36Dshow aberration characteristics at the telephoto position, in focusingof the infinite object point, of the zoom lens in the ninth embodiment.FIGS. 37A-37D show aberration characteristics at the wide-angleposition, in focusing of the short-distance object point, of the zoomlens in the ninth embodiment. FIGS. 38A-38D show aberrationcharacteristics at the middle position, in focusing of theshort-distance object point, of the zoom lens in the ninth embodiment.FIGS. 39A-39D show aberration characteristics at the telephoto position,in focusing of the short-distance object point, of the zoom lens in theninth embodiment.

As shown in FIG. 32, the electronic imaging device of the ninthembodiment has, in order from the object side, a zoom lens and a CCDwhich is an electronic image sensor. In this figure, again, referencesymbol I represents the imaging plane of the CCD. The plane-parallel CCDcover glass CG is interposed between the zoom lens and the imaging planeI.

The zoom lens comprises, in order from the object side, the first lensunit G1, the second lens unit G2 which is the first moving lens unit,the aperture stop S, the third lens unit G3 which is the second movinglens unit, and the fourth lens unit G4.

The first lens unit G1 includes, in order from the object side, thenegative meniscus lens L1 ₁ with a convex surface directed toward theobject side, the reflective optical component R1 having a reflectingsurface for bending the optical path, and the biconvex positive lens L1₂.

The reflective optical component R1 is constructed as a reflecting prismbending the optical path by 90°.

The second lens unit G2 includes, in order from the object side, thecemented lens with the biconcave negative lens L2 ₁ and the positivemeniscus lens L2 ₂ with a convex surface directed toward the objectside, having negative refracting power as a whole.

The third lens unit G3 includes, in order from the object side, thecemented lens with the positive meniscus lens L3 ₁ with a convex surfacedirected toward the object side and the negative meniscus lens L3 ₂ witha convex surface directed toward the object side, and the biconvexpositive lens L3 ₃, having positive refracting power as a whole.

The fourth lens unit G4 includes a cemented lens with the biconcavenegative lens L4 ₁′ and the biconvex positive lens L4 ₂.

When the magnification of the zoom lens is changed, extending from thewide-angle position to the telephoto position, in focusing of theinfinite object point, the first lens unit G1 and the fourth lens unitG4 remain fixed; the second lens unit G2 is moved back and forth on theimage side to follow a convex path (that is, after being moved towardthe image side to widen once spacing between the first lens unit G1 andthe second lens unit G2, narrows the spacing while moving toward theobject side); and the third lens unit G3 is moved toward the object sideonly, together with the aperture stop S.

In focusing of the short-distance object point, the second lens unit G2is shifted to the object side.

The first lens unit G1 and the fourth lens unit G4 remain fixed evenwhen the focusing operation is performed.

Aspherical surfaces are provided to the image-side surface of thenegative meniscus lens L1 ₁ with a convex surface directed toward theobject side in the first lens unit G1, the object-side surface of thepositive meniscus lens L3 ₁ with a convex surface directed toward theobject side in the third lens unit G3, and the image-side surface of thebiconvex positive lens L4 ₂ in the fourth lens unit G4.

Subsequently, numerical data of optical members constituting the zoomlens of the ninth embodiment are shown below.

Numerical data 9 r₁ = 26.5948 d₁ = 0.7000 n_(d1) = 1.80610 ν_(d1) =40.92 r₂ = 5.6908 (aspherical) d₂ = 1.7000 r₃ = ∞ d₃ = 6.8000 n_(d3) =1.80610 ν_(d3) = 40.92 r₄ = ∞ d₄ = 0.1500 r₅ = 12.8103 d₅ = 1.7000n_(d5) = 1.72916 ν_(d3) = 54.68 r₆ = −36.8350 d₆ = D6 r₇ = −6.9505 d₇ =0.7000 n_(d7) = 1.69700 ν_(d7) = 48.52 r₈ = 5.0000 d₈ = 1.5500 n_(d8) =1.84666 ν_(d8) = 23.78 r₉ = 16.5460 d₉ = D9 r₁₀ = ∞ (stop) d₁₀ = 0 r₁₁ =4.4396 (aspherical) d₁₁ = 1.8000 n_(d11) = 1.74320 ν_(d11) = 49.34 r₁₂ =19.0000 d₁₂ = 0.7000 n_(d12) = 1.84666 ν_(d12) = 23.78 r₁₃ = 4.3099 d₁₃= 0.3000 r₁₄ = 7.9340 d₁₄ = 1.7500 n_(d14) = 1.72916 ν_(d14) = 54.68 r₁₅= −9.4658 d₁₅ = D15 r₁₆ = ∞ (position of d₁₆ = 4.4000 variabletransmittance means or shutter) r₁₇ = −11.5780 d₁₇ = 0.7000 n_(d17) =1.80100 ν_(d17) = 34.97 r₁₈ = 20.0000 d₁₈ = 1.3500 n_(d18) = 1.74320ν_(d18) = 49.34 r₁₉ = −9.3722 (aspherical) d₁₉ = 0.7000 r₂₀ = ∞ d₂₀ =0.6000 n_(d20) = 1.51633 ν_(d20) = 64.14 r₂₁ = ∞ d₂₁ = D21 r₂₂ = ∞(imaging plane) d₂₂ = 0 Aspherical coefficients Second surface K = 0 A₂= 0 A₄ = −6.2873 × 10⁻⁴ A₆ = −4.6849 × 10⁻⁷ A₈ = −9.5321 × 10⁻⁷ A₁₀ = 0Eleventh surface K = 0 A₂ = 0 A₄ −1.1790 × 10⁻³ A₆ = 2.6964 × 10⁻⁶ A₈ =−1.5144 × 10⁻⁶ A₁₀ = 0 Nineteenth surface K = 0 A₂ = 0 A₄ = 1.3503 ×10⁻³ A₆ = −5.7711 × 10⁻⁵ A₈ = 1.1904 × 10⁻⁵ A₁₀ = 0

Zoom data Wide-angle Middle Telephoto When the distance D0 is ∞, f(mm)3.26135 5.63695 9.74271 Fno 2.6987 3.3411 4.5499 D0 ∞ ∞ ∞ D6 1.095303.25443 1.09175 D9 8.94170 3.96767 0.88424 D15 1.39037 4.20559 9.45200D21 1.00000 1.00000 1.00000 When the distance D0 is short (16 cm), D0162.6560 162.6560 162.6560 D6 0.92755 3.08080 0.92401 D9 9.10945 4.141311.05198 D15 1.39037 4.20559 9.45200 D21 1.00000 1.00000 1.00000

Tenth Embodiment

FIG. 40 shows an optical arrangement of the tenth embodiment of the zoomlens used in the electronic imaging device according to the presentinvention. FIGS. 41A, 41B, and 41C show optical arrangements atwide-angle, middle, and telephoto positions, respectively, in the tenthembodiment.

As shown in FIG. 40, the electronic imaging device of the tenthembodiment has, in order from the object side, a zoom lens and a CCDwhich is an electronic image sensor. In this figure, again, referencesymbol I represents the imaging plane of the CCD. The plane-parallel CCDcover glass CG is interposed between the zoom lens and the imaging planeI.

The zoom lens comprises, in order from the object side, the first lensunit G1, the second lens unit G2 which is the first moving lens unit,the aperture stop S, the third lens unit G3 which is the second movinglens unit, and the fourth lens unit G4.

The first lens unit G1 includes, in order from the object side, thenegative meniscus lens L1 ₁ with a convex surface directed toward theobject side, the reflective optical component R1 having a reflectingsurface for bending the optical path, and the biconvex positive lens L1₂, having positive refracting power as a whole.

The reflective optical component R1 is constructed as a reflecting prismbending the optical path by 90°.

The second lens unit G2 includes, in order from the object side, thecemented lens with the biconcave negative lens L2 ₁ and the positivemeniscus lens L2 ₂ with a convex surface directed toward the objectside, having negative refracting power as a whole.

The third lens unit G3 includes, in order from the object side, thecemented lens with the positive meniscus lens L3 ₁ with a convex surfacedirected toward the object side and the negative meniscus lens L3 ₂ witha convex surface directed toward the object side, and the biconvexpositive lens L3 ₃, having positive refracting power as a whole.

The fourth lens unit G4 includes a cemented lens with the negativemeniscus lens L4 ₁″ with a concave surface directed toward the objectside and a positive meniscus lens L4 ₂′ with a concave surface directedtoward the object side.

When the magnification of the zoom lens is changed, extending from thewide-angle position to the telephoto position, in focusing of theinfinite object point, the first lens unit G1 and the fourth lens unitG4 remain fixed; the second lens unit G2 is moved back and forth on theimage side to follow a convex path (that is, after being moved towardthe image side to widen once spacing between the first lens unit G1 andthe second lens unit G2, narrows the spacing while moving toward theobject side); and the third lens unit G3 is moved toward the object sideonly, together with the aperture stop S.

In focusing of the short-distance object point, the second lens unit G2is shifted to the object side.

The first lens unit G1 and the fourth lens unit G4 remain fixed evenwhen the focusing operation is performed.

Aspherical surfaces are provided to the image-side surface of thenegative meniscus lens L1 ₁ with a convex surface directed toward theobject side in the first lens unit G1, the object-side surface of thepositive meniscus lens L3 ₁ with a convex surface directed toward theobject side in the third lens unit G3, and the image-side surface of thepositive meniscus lens L4 ₂′ with a concave surface directed toward theobject side in the fourth lens unit G4.

Subsequently, numerical data of optical members constituting the zoomlens of the tenth embodiment are shown below.

Numerical data 10 r₁ = 23.5093 d₁ = 0.7000 n_(d1) = 1.80100 ν_(d1) =34.97 r₂ = 5.3202 (aspherical) d₂ = 1.7000 r₃ = ∞ d₃ = 6.8000 n_(d3) =1.80610 ν_(d3) = 40.92 r₄ = ∞ d₄ = 0.1500 r₅ = 10.3647 d₅ = 1.7000n_(d5) = 1.72916 ν_(d5) = 54.68 r₆ = −47.4421 d₆ = D6 r₇ = −7.2232 d₇ =0.7000 n_(d7) = 1.69680 ν_(d7) = 55.53 r₈ = 5.0000 d₈ = 1.5500 n_(d8) =1.84666 ν_(d8) = 23.78 r₉ = 13.6636 d₉ = D9 r₁₀ = ∞ (stop) d₁₀ = 0 r₁₁ =4.2851 (aspherical) d₁₁ = 1.8000 n_(d11) = 1.69350 ν_(d11) = 53.21 r₁₂ =19.0000 d₁₂ = 0.7000 n_(d12) = 1.84666 ν_(d12) = 23.78 r₁₃ = 4.3542 d₁₃= 0.3000 r₁₄ = 7.5927 d₁₄ = 1.7500 n_(d14) = 1.72916 ν_(d14) = 54.68 r₁₅= −9.0883 d₁₅ = D15 r₁₆ = ∞ (position of variable d₁₆ = 4.4000transmittance means or shutter) r₁₇ = −7.8172 d₁₇ = 0.7000 n_(d17) =1.84666 ν_(d17) = 23.78 r₁₈ = −50.0000 d₁₈ = 1.3500 n_(d18) = 1.74320ν_(d18) = 49.34 r₁₉ = −7.2821 (aspherical) d₁₉ = 0.7000 r₂₀ = ∞ d₂₀ =0.6000 n_(d20) = 1.51633 ν_(d20) = 64.14 r₂₁ = ∞ d₂₁ = D21 r₂₂ = ∞(imaging plane) d₂₂ = 0 Aspherical coefficients Second surface K = 0 A₂= 0 A₄ = −7.4556 × 10⁻⁴ A₆ = 3.8977 × 10⁻⁶ A₈ = −1.6059 × 10⁻⁶ A₁₀ = 0Eleventh surface K = 0 A₂ = 0 A₄ = −1.4222 × 10⁻³ A₆ = −8.4545 × 10⁻⁷ A₈= −1.7364 × 10⁻⁶ A₁₀ = 0 Nineteenth surface K = 0 A₂ = 0 A₄ = 1.5497 ×10⁻³ A₆ = −1.9296 × 10⁻⁴ A₈ = 3.0021 × 10⁻⁵ A₁₀ = 0

Zoom data Wide-angle Middle Telephoto When the distance D0 is ∞, f(mm)3.26990 5.62502 9.73871 Fno 2.7015 3.2638 4.4073 D0 ∞ ∞ ∞ D6 1.091083.56834 1.99910 D9 9.07726 4.16755 0.88213 D15 1.21117 3.63605 8.49846D21 1.00000 1.00000 1.00000 When the distance D0 is short (16 cm), D0162.6560 162.6560 162.6560 D6 0.92058 3.38281 1.82331 D9 9.24776 4.353081.05792 D15 1.21117 3.63605 8.49846 D21 1.00000 1.00000 1.00000

Eleventh Embodiment

FIG. 42 shows an optical arrangement of the eleventh embodiment of thezoom lens used in the electronic imaging device according to the presentinvention. FIGS. 43A, 43B, and 43C show optical arrangements atwide-angle, middle, and telephoto positions, respectively, in theeleventh embodiment. FIGS. 44A-44D show aberration characteristics atthe wide-angle position, in focusing of the infinite object point, ofthe zoom lens in the eleventh embodiment. FIGS. 45A-45D show aberrationcharacteristics at the middle position, in focusing of the infiniteobject point, of the zoom lens in the eleventh embodiment. FIGS. 46A-46Dshow aberration characteristics at the telephoto position, in focusingof the infinite object point, of the zoom lens in the eleventhembodiment. FIGS. 47A-47D show aberration characteristics at thewide-angle position, in focusing of the short-distance object point, ofthe zoom lens in the eleventh embodiment. FIGS. 48A-48D show aberrationcharacteristics at the middle position, in focusing of theshort-distance object point, of the zoom lens in the eleventhembodiment. FIGS. 49A-49D show aberration characteristics at thetelephoto position, in focusing of the short-distance object point, ofthe zoom lens in the eleventh embodiment.

As shown in FIG. 42, the electronic imaging device of the eleventhembodiment has, in order from the object side, a zoom lens and a CCDwhich is an electronic image sensor. In this figure, again, referencesymbol I represents the imaging plane of the CCD. The plane-parallel CCDcover glass CG is interposed between the zoom lens and the imaging planeI.

The zoom lens comprises, in order from the object side, the first lensunit G1, the second lens unit G2 which is the first moving lens unit,the aperture stop S, the third lens unit G3 which is the second movinglens unit, and the fourth lens unit G4.

The first lens unit G1 includes, in order from the object side, thenegative meniscus lens L1 ₁ with a convex surface directed toward theobject side, the reflective optical component R1 having a reflectingsurface for bending the optical path, and the biconvex positive lens L1₂, having positive refracting power as a whole.

The reflective optical component R1 is constructed as a reflecting prismbending the optical path by 90°.

The second lens unit G2 includes, in order from the object side, thecemented lens with the biconcave negative lens L2 ₁ and the positivemeniscus lens L2 ₂ with a convex surface directed toward the objectside, having negative refracting power as a whole.

The third lens unit G3 includes, in order from the object side, thecemented lens with the positive meniscus lens L3 ₁ with a convex surfacedirected toward the object side and the negative meniscus lens L3 ₂ witha convex surface directed toward the object side, and the biconvexpositive lens L3 ₃, having positive refracting power as a whole.

The fourth lens unit G4 includes a positive meniscus lens L4 ₁′″ with aconcave surface directed toward the object side.

When the magnification of the zoom lens is changed, extending from thewide-angle position to the telephoto position, in focusing of theinfinite object point, the first lens unit G1 and the fourth lens unitG4 remain fixed; the second lens unit G2 is moved back and forth on theimage side to follow a convex path (that is, after being moved towardthe image side to widen once spacing between the first lens unit G1 andthe second lens unit G2, narrows the spacing while moving toward theobject side); and the third lens unit G3 is moved toward the object sideonly, together with the aperture stop S.

In focusing of the short-distance object point, the second lens unit G2is shifted to the object side.

The first lens unit G1 and the fourth lens unit G4 remain fixed evenwhen the focusing operation is performed.

Aspherical surfaces are provided to the image-side surface of thenegative meniscus lens L1 ₁ with a convex surface directed toward theobject side in the first lens unit G1, the object-side surface of thepositive meniscus lens L3 ₁ with a convex surface directed toward theobject side in the third lens unit G3, and the image-side surface of thepositive meniscus lens L4 ₁′″ with a concave surface directed toward theobject side, constituting the fourth lens unit G4.

Subsequently, numerical data of optical members constituting the zoomlens of the eleventh embodiment are shown below.

Numerical data 11 r₁ = 29.7756 d₁ = 0.7000 n_(d1) = 1.80610 ν_(d1) =40.92 r₂ = 5.5894 (aspherical) d₂ = 1.7000 r₃ = ∞ d₃ = 6.8000 n_(d3) =1.80610 ν_(d3) = 40.92 r₄ = ∞ d₄ = 0.1500 r₅ = 12.5603 d₅ = 1.7500n_(d5) = 1.72916 ν_(d5) = 54.68 r₆ = −28.7102 d₆ = D6 r₇ = −7.7962 d₇ =0.7000 n_(d7) = 1.69700 ν_(d7) = 48.52 r₈ = 5.0000 d₈ = 1.6000 n_(d8) =1.84666 ν_(d8) = 23.78 r₉ = 15.2398 d₉ = D9 r₁₀ = ∞ (stop) d₁₀ = 0 r₁₁ =4.2660 (aspherical) d₁₁ = 1.8000 n_(d11) = 1.74320 ν_(d11) = 49.34 r₁₂ =17.0000 d₁₂ = 0.7000 n_(d12) = 1.84666 ν_(d12) = 23.78 r₁₃ = 3.9877 d₁₃= 0.3000 r₁₄ = 7.3491 d₁₄ = 1.7000 n_(d14) = 1.72916 ν_(d14) = 54.68 r₁₅= −11.3337 d₁₅ = 0.9338 r₁₆ = ∞ (position of d₁₆ = 5.4000 variabletransmittance means or shutter) r₁₇ = −20.8118 d₁₇ = 1.0000 n_(d17) =1.58313 ν_(d17) = 59.38 r₁₈ = −11.2032 (aspherical) d₁₈ = 0.7000 r₁₉ = ∞d₁₉ = 0.6000 n_(d19) = 1.51633 ν_(d19) = 64.14 r₂₀ = ∞ d₂₀ = D20 r₂₂ = ∞(imaging plane) d₂₂ = 0 Aspherical coefficients Second surface K = 0 A₂= 0 A₄ = −6.3979 × 10⁻⁴ A₆ = −7.5270 × 10⁻⁷ A₈ = −9.7517 × 10⁻⁷ A₁₀ = 0Eleventh surface K = 0 A₂ = 0 A₄ = −1.0377 × 10⁻³ A₆ = −2.4735 × 10⁻⁶ A₈= −2.0035 × 10⁻⁶ A₁₀ = 0 Eighteenth surface K = 0 A₂ = 0 A₄ = 1.1850 ×10⁻³ A₆ = 1.2885 × 10⁻⁴ A₈ = −1.2384 × 10⁻⁵ A₁₀ = 0

Zoom data Wide-angle Middle Telephoto When the distance D0 is ∞, f(mm)3.25682 5.63853 9.74463 Fno 2.6426 3.2679 4.5140 D0 ∞ ∞ ∞ D6 1.096073.39481 1.09365 D9 9.37627 4.21600 0.88753 D15 0.93379 3.79716 9.42548D21 1.00000 1.00000 1.00000 When the distance D0 is short (16 cm), D0162.6560 162.6560 162.6560 D6 0.89495 3.18037 0.89254 D9 9.57739 4.430441.08864 D15 0.93379 3.79716 9.42548 D21 1.00000 1.00000 1.00000

Twelfth Embodiment

FIG. 50 shows an optical arrangement of the twelfth embodiment of thezoom lens used in the electronic imaging device according to the presentinvention. FIGS. 51A, 51B, and 51C show optical arrangements atwide-angle, middle, and telephoto positions, respectively, in thetwelfth embodiment. FIGS. 52A-52D show aberration characteristics at thewide-angle position, in focusing of the infinite object point, of thezoom lens in the twelfth embodiment. FIGS. 53A-53D show aberrationcharacteristics at the middle position, in focusing of the infiniteobject point, of the zoom lens in the twelfth embodiment. FIGS. 54A-54Dshow aberration characteristics at the telephoto position, in focusingof the infinite object point, of the zoom lens in the twelfthembodiment. FIGS. 55A-55D show aberration characteristics at thewide-angle position, in focusing of the short-distance object point, ofthe zoom lens in the twelfth embodiment. FIGS. 56A-56D show aberrationcharacteristics at the middle position, in focusing of theshort-distance object point, of the zoom lens in the twelfth embodiment.FIGS. 57A-57D show aberration characteristics at the telephoto position,in focusing of the short-distance object point, of the zoom lens in thetwelfth embodiment.

As shown in FIG. 50, the electronic imaging device of the twelfthembodiment has, in order from the object side, a zoom lens and a CCDwhich is an electronic image sensor. In this figure, again, referencesymbol I represents the imaging plane of the CCD. The plane-parallel CCDcover glass CG is interposed between the zoom lens and the imaging planeI.

The zoom lens comprises, in order from the object side, the first lensunit G1, the second lens unit G2 which is the first moving lens unit,the aperture stop S, the third lens unit G3 which is the second movinglens unit, and the fourth lens unit G4.

The first lens unit G1 includes, in order from the object side, thenegative meniscus lens L1 ₁ with a convex surface directed toward theobject side, the reflective optical component R1 having a reflectingsurface for bending the optical path, and the biconvex positive lens L1₂, having positive refracting power as a whole.

The reflective optical component R1 is constructed as a reflecting prismbending the optical path by 90°.

The second lens unit G2 includes, in order from the object side, thecemented lens with the biconcave negative lens L2 ₁ and the positivemeniscus lens L2 ₂ with a convex surface directed toward the objectside, having negative refracting power as a whole.

The third lens unit G3 includes, in order from the object side, thecemented lens with the positive meniscus lens L3 ₁ with a convex surfacedirected toward the object side and the negative meniscus lens L3 ₂ witha convex surface directed toward the object side, and the biconvexpositive lens L3 ₃, having positive refracting power as a whole.

The fourth lens unit G4 includes the cemented lens with the negativemeniscus lens L4 ₁″ with a concave surface directed toward the objectside and the positive meniscus lens L4 ₂′ with a concave surfacedirected toward the object side.

When the magnification of the zoom lens is changed, extending from thewide-angle position to the telephoto position, in focusing of theinfinite object point, the first lens unit G1 remains fixed; the secondlens unit G2 is moved toward the object side only; the third lens unitG3 is moved toward the object side only, together with the aperture stopS; and the fourth lens unit G4 is moved back and forth on the image sideto follow a convex path (that is, after being moved toward the objectside to widen once spacing between the fourth lens unit G4 and the CCDcover glass CG, narrows the spacing while moving toward the image side).

In focusing of the short-distance object point, the second lens unit G2is shifted to the object side.

Also, when the first lens unit G1 and the fourth lens unit G4 remainfixed when the focusing operation is performed.

Aspherical surfaces are provided to the image-side surface of thenegative meniscus lens L1 ₁ with a convex surface directed toward theobject side in the first lens unit G1, the object-side surface of thepositive meniscus lens L3 ₁ with a convex surface directed toward theobject side in the third lens unit G3, and the image-side surface of thepositive meniscus lens L4 ₁′ with a concave surface directed toward theobject side in the fourth lens unit G4.

Subsequently, numerical data of optical members constituting the zoomlens of the twelfth embodiment are shown below.

Numerical data 12 r₁ = 18.8862 d₁ = 0.7000 n_(d1) = 1.80100 ν_(d1) =34.97 r₂ = 4.8033 (aspherical) d₂ = 1.7000 r₃ = ∞ d₃ = 6.8000 n_(d3) =1.80610 ν_(d3) = 40.92 r₄ = ∞ d₄ = 0.1500 r₅ = 13.4964 d₅ = 2.3000n_(d5) = 1.61800 ν_(d5) = 63.33 r₆ = −11.1385 d₆ = D6 r₇ = −8.8071 d₇ =0.7000 n_(d7) = 1.69680 ν_(d7) = 55.53 r₈ = 4.9069 d₈ = 1.5500 n_(d8) =1.84666 ν_(d8) = 23.78 r₉ = 9.5429 d₉ = D9 r₁₀ = ∞ (stop) d₁₀ = 0 r₁₁ =4.0853 (aspherical) d₁₁ = 1.8000 n_(d11) = 1.69350 ν_(d11) = 53.21 r₂ =11.0960 d₁₂ = 0.7000 n_(d12) = 1.84666 ν_(d12) = 23.78 r₁₃ = 3.9813 d₁₃= 0.3000 r₁₄ = 5.9541 d₁₄ = 1.9500 n_(d14) = 1.72916 ν_(d14) = 54.68 r₁₅= −9.8112 d₁₅ = D15 r₁₆ = ∞ (position of d₁₆ = D16 variabletransmittance means or shutter) r₁₇ = −3.5444 d₁₇ = 0.7000 n_(d17) =1.84666 ν_(d17) = 23.78 r₁₈ = −10.0000 d₁₈ = 1.3500 n_(d18) = 1.74320ν_(d18) = 49.34 r₁₉ = −4.2449 (aspherical) d₁₉ = D19 r₂₀ = ∞ d₂₀ =0.6000 n_(d20) = 1.51633 ν_(d20) = 64.14 r₂₁ = ∞ d₂₁ = D21 r₂₂ = ∞(imaging plane) d₂₂ = 0 Aspherical coefficients Second surface K = 0 A₂= 0 A₄ = −5.1721 × 10⁻⁴ A₆ = −1.0392 × 10⁻⁶ A₈ = −2.0432 × 10⁻⁶ A₁₀ = 0Eleventh surface K = 0 A₂ = 0 A₄ = −1.4943 × 10⁻³ A₆ = −5.7721 × 10⁻⁶ A₈= −3.1513 × 10⁻⁶ A₁₀ = 0 Nineteenth surface K = 0 A₂ = 0 A₄ = 4.5325 ×10⁻⁴ A₆ = 2.3664 × 10⁻⁴ A₈ = −1.3755 × 10⁻⁵ A₁₀ = 0

Zoom data Wide-angle Middle Telephoto When the distance D0 is ∞, f(mm)3.29281 5.63775 9.72059 Fno 2.7263 3.1514 3.8592 D0 ∞ ∞ ∞ D6 1.084483.76500 4.99556 D9 9.23562 4.42709 0.86778 D15 0.70863 2.83776 5.16580D16 3.84796 2.38541 3.84796 D19 0.89838 2.35813 0.88807 D21 1.000001.00000 1.00000 When the distance D0 is short (16 cm), D0 162.6560162.6560 162.6560 D6 0.89908 3.53214 4.73441 D9 9.42102 4.65996 1.12893D15 0.70863 2.83776 5.16580 D16 3.84796 2.38541 3.85876 D19 0.898382.35813 0.88807 D21 1.00000 1.00000 1.00000

Thirteenth Embodiment

FIG. 58 shows an optical arrangement of the thirteenth embodiment of thezoom lens used in the electronic imaging device according to the presentinvention. FIGS. 59A, 59B, and 59C show optical arrangements atwide-angle, middle, and telephoto positions, respectively, in thethirteenth embodiment. FIGS. 60A-60D show aberration characteristics atthe wide-angle position, in focusing of the infinite object point, ofthe zoom lens in the thirteenth embodiment. FIGS. 61A-61D showaberration characteristics at the middle position, in focusing of theinfinite object point, of the zoom lens in the thirteenth embodiment.FIGS. 62A-62D show aberration characteristics at the telephoto position,in focusing of the infinite object point, of the zoom lens in thethirteenth embodiment. FIGS. 63A-63D show aberration characteristics atthe wide-angle position, in focusing of the short-distance object point,of the zoom lens in the thirteenth embodiment. FIGS. 64A-64D showaberration characteristics at the middle position, in focusing of theshort-distance object point, of the zoom lens in the thirteenthembodiment. FIGS. 65A-65D show aberration characteristics at thetelephoto position, in focusing of the short-distance object point, ofthe zoom lens in the thirteenth embodiment.

As shown in FIG. 58, the electronic imaging device of the thirteenthembodiment has, in order from the object side, a zoom lens and a CCDwhich is an electronic image sensor. In this figure, again, referencesymbol I represents the imaging plane of the CCD. The plane-parallel CCDcover glass CG is interposed between the zoom lens and the imaging planeI.

The zoom lens comprises, in order from the object side, the first lensunit G1, the second lens unit G2 which is the first moving lens unit,the aperture stop S, the third lens unit G3 which is the second movinglens unit, and the fourth lens unit G4.

The first lens unit G1 includes, in order from the object side, thenegative meniscus lens L1 ₁ with a convex surface directed toward theobject side, the reflective optical component R1 having a reflectingsurface for bending the optical path, and the positive meniscus lens L1₂′ with a convex surface directed toward the object side, havingpositive refracting power as a whole.

The reflective optical component R1 is constructed as a reflecting prismbending the optical path by 90°.

The second lens unit G2 includes, in order from the object side, thecemented lens with the biconcave negative lens L2 ₁ and the positivemeniscus lens L2 ₂ with a convex surface directed toward the objectside, having negative refracting power as a whole.

The third lens unit G3 includes, in order from the object side, thebiconvex positive lens L3 ₁ and the cemented lens with the positivemeniscus lens L3 ₂′ with a convex surface directed toward the objectside and the negative meniscus lens L3 ₃′ with a convex surface directedtoward the object side, having positive refracting power as a whole.

The fourth lens unit G4 includes the positive meniscus lens L4 ₁′″ witha concave surface directed toward the object side.

When the magnification of the zoom lens is changed, extending from thewide-angle position to the telephoto position, in focusing of theinfinite object point, the first lens unit G1 and the fourth lens unitG4 remain fixed; the second lens unit G2 is moved back and forth on theimage side to follow a convex path (that is, after being moved towardthe image side to widen once spacing between the first lens unit G1 andthe second lens unit G2, narrows the spacing while moving toward theobject side); and the third lens unit G3 is moved toward the object sideonly, together with the aperture stop S.

In focusing of the short-distance object point, the second lens unit G2is shifted to the object side.

Also, when the first lens unit G1 and the fourth lens unit G4 remainfixed even when the focusing operation is performed.

Aspherical surfaces are provided to the image-side surface of thenegative meniscus lens L1 ₁ with a convex surface directed toward theobject side in the first lens unit G1, the image-side surface of thebiconvex positive lens L3 ₁′ in the third lens unit G3, and theimage-side surface of the positive meniscus lens L4 ₁′″ with a concavesurface directed toward the object side, constituting the fourth lensunit G4.

Subsequently, numerical data of optical members constituting the zoomlens of the thirteenth embodiment are shown below.

Numerical data 13 r₁ = 39.8371 d₁ = 0.9000 n_(d1) = 1.74320 ν_(d1) =49.34 r₂ = 7.0363 (aspherical) d₂ = 1.9500 r₃ = ∞ d₃ = 8.4000 n_(d3) =1.80610 ν_(d3) = 40.92 r₄ = ∞ d₄ = 0.1500 r₅ = 10.7443 d₅ = 1.7500n_(d5) = 1.72916 ν_(d5) = 54.68 r₆ = 117.6949 d₆ = D6 r₇ = −11.0080 d₇ =0.7000 n_(d7) = 1.72916 ν_(d7) = 54.68 r₈ = 10.0000 d₈ = 1.3500 n_(d8) =1.84666 ν_(d8) = 23.78 r₉ = 29.9687 d₉ = D9 r₁₀ = ∞ (stop) d₁₀ = 0 r₁₁ =8.9151 d₁₁ = 1.7000 n_(d11) = 1.58313 ν_(d11) = 59.38 r₁₂ = −9.9490 d₁₂= 0.1500 (aspherical) r₁₃ = 3.8299 d₁₃ = 1.9500 n_(d13) = 1.69350ν_(d13) = 53.21 r₁₄ = 40.0000 d₁₄ = 0.7000 n_(d14) = 1.78740 ν_(d14) =26.29 r₁₅ = 2.5278 d₁₅ = 1.6250 r₁₆ = ∞ (position d₁₆ = D16 of variabletransmittance means or shutter) r₁₇ = −75.2976 d₁₇ = 1.6000 n_(d17) =1.68893 ν_(d17) = 31.07 r₁₈ = −6.9567 d₁₈ = 0.6000 (aspherical) r₁₉ = ∞d₁₉ = 0.7500 n_(d19) = 1.51633 ν_(d19) = 64.14 r₂₀ = ∞ d₂₀ = D20 r₂₁ = ∞(imaging plane) d₂₁ = 0 Aspherical coefficients Second surface K = 0 A₂= 0 A₄ = −3.2095 × 10⁻⁴ A₆ = 3.5914 × 10⁻⁶ A₈ = −2.3288 × 10⁻⁷ A₁₀ = 0Twelfth surface K = 0 A₂ = 0 A₄ = 7.8959 × 10⁻⁴ A₆ = −8.1489 × 10⁻⁶ A₈ =8.1947 × 10⁻⁷ A₁₀ = 0 Eighteenth surface K = 0 A₂ = 0 A₄ = 1.5904 × 10⁻³A₆ = −7.4738 × 10⁻⁵ A₈ = 1.6824 × 10⁻⁶ A₁₀ = 0

Zoom data Wide-angle Middle Telephoto When the distance D0 is ∞, f(mm)4.00704 6.93144 11.99933 Fno 2.6299 3.4603 5.0206 D0 ∞ ∞ ∞ D6 1.339843.55821 1.33955 D9 8.82987 3.72328 0.59893 D16 2.39220 5.27920 10.62359D20 1.00000 1.00000 1.00000 When the distance D0 is short (20 cm), D0200.0000 200.0000 200.0000 D6 0.99920 3.20721 0.99891 D9 9.17052 4.074280.93957 D16 2.39220 5.27920 10.62359 D20 1.00000 1.00000 1.00000

Fourteenth Embodiment

FIG. 66 shows an optical arrangement of the fourteenth embodiment of thezoom lens used in the electronic imaging device according to the presentinvention. FIGS. 67A, 67B, and 67C show optical arrangements atwide-angle, middle, and telephoto positions, respectively, in thefourteenth embodiment.

As shown in FIG. 66, the electronic imaging device of the fourteenthembodiment has, in order from the object side, a zoom lens and a CCDwhich is an electronic image sensor. In this figure, again, referencesymbol I represents the imaging plane of the CCD. The plane-parallel CCDcover glass CG is interposed between the zoom lens and the imaging planeI.

The zoom lens comprises, in order from the object side, the first lensunit G1, the second lens unit G2 which is the first moving lens unit,the aperture stop S, the third lens unit G3 which is the second movinglens unit, and the fourth lens unit G4.

The first lens unit G1 includes, in order from the object side, thenegative meniscus lens L1 ₁ with a convex surface directed toward theobject side, the reflective optical component R1 having a reflectingsurface for bending the optical path, and the positive meniscus lens L1₂′ with a convex surface directed toward the object side, havingpositive refracting power as a whole.

The reflective optical component R1 is constructed as a reflecting prismbending the optical path by 90°.

The second lens unit G2 includes, in order from the object side, thecemented lens with the biconcave negative lens L2 ₁ and the positivemeniscus lens L2 ₂ with a convex surface directed toward the objectside, having negative refracting power as a whole.

The third lens unit G3 includes, in order from the object side, thebiconvex positive lens L3 ₁′ and the cemented lens with the positivemeniscus lens L3 ₂′ with a convex surface directed toward the objectside and the negative meniscus lens L3 ₃′ with a convex surface directedtoward the object side, having positive refracting power as a whole.

The fourth lens unit G4 includes the positive meniscus lens L4 ₁′″ witha concave surface directed toward the object side.

When the magnification of the zoom lens is changed, extending from thewide-angle position to the telephoto position, in focusing of theinfinite object point, the first lens unit G1 and the fourth lens unitG4 remain fixed; the second lens unit G2 is moved back and forth on theimage side to follow a convex path (that is, after being moved towardthe image side to widen once spacing between the first lens unit G1 andthe second lens unit G2, narrows the spacing while moving toward theobject side); and the third lens unit G3 is moved toward the object sideonly, together with the aperture stop S.

In focusing of the short-distance object point, the second lens unit G2is shifted to the object side.

Also, when the first lens unit G1 and the fourth lens unit G4 remainfixed even when the focusing operation is performed.

Aspherical surfaces are provided to the image-side surface of thenegative meniscus lens L1 ₁ with a convex surface directed toward theobject side in the first lens unit G1, the object-side surface of thepositive meniscus lens L3 ₂′ with a convex surface directed toward theobject side in the third lens unit G3, and the image-side surface of thepositive meniscus lens L4 ₁′″ with a concave surface directed toward theobject side, constituting the fourth lens unit G4.

Subsequently, numerical data of optical members constituting the zoomlens of the fourteenth embodiment are shown below.

Numerical data 14 r₁ = 46.4345 d₁ = 0.9000 n_(d1) = 1.74320 ν_(d1) =49.34 r₂ = 7.4800 d₂ = 1.9000 (aspherical) r₃ = ∞ d₃ = 8.4000 n_(d3) =1.80610 ν_(d3) = 40.92 r₄ = ∞ d₄ = 0.1500 r₅ = 10.9290 d₅ = 1.7000n_(d5) = 1.72916 ν_(d5) = 54.68 r₆ = 79.8760 d₆ = D6 r₇ = −9.0602 d₇ =0.7000 n_(d7) = 1.72916 ν_(d7) = 54.68 r₈ = 10.0000 d₈ = 1.3500 n_(d8) =1.80518 ν_(d8) = 25.42 r₉ = 79.0547 d₉ = D9 r₁₀ = ∞ (stop) d₁₀ = 0 r₁₁ =12.8072 d₁₁ = 1.8000 n_(d11) = 1.48749 ν_(d11) = 70.23 r₁₂ = −7.7890 d₁₂= 0.1500 r₁₃ = 3.3563 (aspherical) d₁₃ = 2.0000 n_(d13) = 1.74320ν_(d13) = 49.34 r₁₄ = 10.0000 d₁₄ = 0.7000 n_(d14) = 1.84666 ν_(d14) =23.78 r₁₅ = 2.3358 d₁₅ = 1.6250 r₁₆ = ∞ (position d₁₆ = D16 of variabletransmittance means or shutter) r₁₇ = −32.6186 d₁₇ = 1.6000 n_(d17) =1.68893 ν_(d17) = 31.07 r₁₈ = −6.3725 d₁₈ = 0.6000 (aspherical) r₁₉ = ∞d₁₉ = 0.7500 n_(d19) = 1.51633 ν_(d19) = 64.14 r₂₀ = ∞ d₂₀ = D20 r₂₁ = ∞d₂₁ = 0 (imaging plane) Aspherical coefficients Second surface K = 0 A₂= 0 A₄ = −3.0741 × 10⁻⁴ A₆ = 2.9868 × 10⁻⁶ A₈ = −2.2074 × 10⁻⁷ A₁₀ = 0Thirteenth surface K = 0 A₂ = 0 A₄ = −8.6447 × 10⁻⁴ A₆ = −2.3383 × 10⁻⁵A₈ = −1.1764 × 10⁻⁵ A₁₀ = 0 Eighteenth surface K = 0 A₂ = 0 A₄ = 1.7917× 10⁻³ A₆ = −8.0795 × 10⁻⁵ A₈ = 2.0929 × 10⁻⁶ A₁₀ = 0

Zoom data Wide-angle Middle Telephoto When the distance D0 is ∞ f(mm)4.00365 6.92795 12.00080 Fno 2.6033 3.4480 5.0024 D0 ∞ ∞ ∞ D6 1.327373.52064 1.32840 D9 8.76178 3.65332 0.60135 D16 2.39254 5.30046 10.55195D20 1.00000 1.00000 1.00000 When the distance D0 is short (20 cm), D0200.0000 200.0000 200.0000 D6 0.99975 3.18799 1.00078 D9 9.08940 3.985980.92898 D16 2.39254 5.30046 10.55195 D20 1.00000 1.00000 1.00000

Fifteenth Embodiment

FIG. 68 shows an optical arrangement of the fifteenth embodiment of thezoom lens used in the electronic imaging device according to the presentinvention. FIGS. 69A, 69B, and 69C show optical arrangements atwide-angle, middle, and telephoto positions, respectively, in thefifteenth embodiment.

As shown in FIG. 68, the electronic imaging device of the fifteenthembodiment has, in order from the object side, a zoom lens and a CCDwhich is an electronic image sensor. In this figure, again, referencesymbol I represents the imaging plane of the CCD. The plane-parallel CCDcover glass CG is interposed between the zoom lens and the imaging planeI.

The zoom lens comprises, in order from the object side, the first lensunit G1, the second lens unit G2 which is the first moving lens unit,the aperture stop S, the third lens unit G3 which is the second movinglens unit, and the fourth lens unit G4.

The first lens unit G1 includes, in order from the object side, thenegative meniscus lens L1 ₁ with a convex surface directed toward theobject side, the reflective optical component R1 having a reflectingsurface for bending the optical path, and the positive meniscus lens L1₂′ with a convex surface directed toward the object side, havingpositive refracting power as a whole.

The reflective optical component R1 is constructed as a reflecting prismbending the optical path by 90°.

The second lens unit G2 includes, in order from the object side, thecemented lens with the biconcave negative lens L2 ₁ and the positivemeniscus lens L2 ₂ with a convex surface directed toward the objectside, having negative refracting power as a whole.

The third lens unit G3 includes, in order from the object side, thebiconvex positive lens L3 ₁′ and the cemented lens with the positivemeniscus lens L3 ₂′ with a convex surface directed toward the objectside and the negative meniscus lens L3 ₃′ with a convex surface directedtoward the object side, having positive refracting power as a whole.

The fourth lens unit G4 includes the positive meniscus lens L4 ₁′″ witha concave surface directed toward the object side.

When the magnification of the zoom lens is changed, extending from thewide-angle position to the telephoto position, in focusing of theinfinite object point, the first lens unit G1 and the fourth lens unitG4 remain fixed; the second lens unit G2 is moved back and forth on theimage side to follow a convex path (that is, after being moved towardthe image side to widen once spacing between the first lens unit G1 andthe second lens unit G2, narrows the spacing while moving toward theobject side); and the third lens unit G3 is moved toward the object sideonly, together with the aperture stop S.

In focusing of the short-distance object point, the second lens unit G2is shifted to the object side.

Also, when the first lens unit G1 and the fourth lens unit G4 remainfixed even when the focusing operation is performed.

Aspherical surfaces are provided to the image-side surface of thenegative meniscus lens L1 ₁ with a convex surface directed toward theobject side in the first lens unit G1, the object-side surface of thebiconvex positive lens L3 ₁′ in the third lens unit G3, and theimage-side surface of the positive meniscus lens L4 ₁′″ with a concavesurface directed toward the object side, constituting the fourth lensunit G4.

Subsequently, numerical data of optical members constituting the zoomlens of the fifteenth embodiment are shown below.

Numerical data 15 r₁ = 39.9121 d₁ = 0.9000 n_(d1) = 1.74320 ν_(d1) =49.34 r₂ = 7.0006 d₂ = 1.9500 (aspherical) r₃ = ∞ d₃ = 8.4000 n_(d3) =1.80610 ν_(d3) = 40.92 r₄ = ∞ d₄ = 0.1500 r₅ = 10.6090 d₅ = 1.7500n_(d5) = 1.72916 ν_(d5) = 54.68 r₆ = 147.0043 d₆ = D6 r₇ = −10.9916 d₇ =0.7000 n_(d7) = 1.72916 ν_(d7) = 54.68 r₈ = 10.0000 d₈ = 1.3500 n_(d8) =1.84666 ν_(d8) = 23.78 r₉ = 28.2731 d₉ = D9 r₁₀ = ∞ d₁₀ = 0 (aspherical)r₁₁ = 9.1551 d₁₁ = 1.7000 n_(d11) = 1.58313 ν_(d11) = 59.38 (aspherical)r₁₂ = −9.4402 d₁₂ = 0.1500 r₁₃ = 3.8548 d₁₃ = 1.9500 n_(d13) = 1.69350ν_(d13) = 53.21 r₁₄ = 40.0000 d₁₄ = 0.7000 n_(d14) = 1.78470 ν_(d14) =26.29 r₁₅ = 2.5225 d₁₅ = D15 r₁₆ = ∞ d₁₆ = 2.8250 (position of variabletransmittance means or shutter) r₁₇ = −85.1906 d₁₇ = 1.6000 n_(d17) =1.68893 ν_(d17) = 31.07 r₁₈ = −7.0057 d₁₈ = 0.6000 (aspherical) r₁₉ = ∞d₁₉ = 0.7500 n_(d19) = 1.51633 ν_(d19) = 64.14 r₂₀ = ∞ d₂₀ = D20 r₂₁ = ∞d₂₁ = 0 (imaging plane) Aspherical coefficients Second surface K = 0 A₂= 0 A₄ = −3.2240 × 10⁻⁴ A₆ = 3.7049 × 10⁻⁶ A₈ = −2.5408 × 10⁻⁷ A₁₀ = 0Eleventh surface K = 0 A₂ = 0 A₄ = −7.8694 × 10⁻⁴ A₆ = 5.1170 × 10⁻⁶ A₈= −2.0804 × 10⁻⁷ A₁₀ = 0 Eighteenth surface K = 0 A₂ = 0 A₄ = 1.5375 ×10⁻³ A₆ = −6.5569 × 10⁻⁵ A₈ = 1.0698 × 10⁻⁶ A₁₀ = 0

Zoom data Wide-angle Middle Telephoto When the distance D0 is ∞, f(mm)4.00716 6.92905 12.00056 Fno 2.6214 3.4396 5.0196 D0 ∞ ∞ ∞ D6 1.342783.57165 1.34265 D9 8.82741 3.75134 0.59749 D15 1.18816 4.03385 9.41834D20 1.00000 1.00000 1.00000 When the distance DO is short (20 cm), D0200.0000 200.0000 200.0000 D6 0.99949 3.21410 0.99936 D9 9.17070 4.108890.94079 D15 1.18816 4.03385 9.41834 D20 1.00000 1.00000 1.00000

Sixteenth Embodiment

FIG. 70 shows an optical arrangement of the sixteenth embodiment of thezoom lens used in the electronic imaging device according to the presentinvention. FIGS. 71A, 71B, and 71C show optical arrangements atwide-angle, middle, and telephoto positions, respectively, in thesixteenth embodiment. FIGS. 72A-72D show aberration characteristics atthe wide-angle position, in focusing of the infinite object point, ofthe zoom lens in the sixteenth embodiment. FIGS. 73A-73D show aberrationcharacteristics at the middle position, in focusing of the infiniteobject point, of the zoom lens in the sixteenth embodiment. FIGS.74A-74D show aberration characteristics at the telephoto position, infocusing of the infinite object point, of the zoom lens in the sixteenthembodiment. FIGS. 75A-75D show aberration characteristics at thewide-angle position, in focusing of the short-distance object point, ofthe zoom lens in the sixteenth embodiment. FIGS. 76A-76D show aberrationcharacteristics at the middle position, in focusing of theshort-distance object point, of the zoom lens in the sixteenthembodiment. FIGS. 77A-77D show aberration characteristics at thetelephoto position, in focusing of the short-distance object point, ofthe zoom lens in the sixteenth embodiment.

As shown in FIG. 70, the electronic imaging device of the sixteenthembodiment has, in order from the object side, a zoom lens and a CCDwhich is an electronic image sensor. In this figure, again, referencesymbol I represents the imaging plane of the CCD. The plane-parallel CCDcover glass CG is interposed between the zoom lens and the imaging planeI.

The zoom lens comprises, in order from the object side, the first lensunit G1, the second lens unit G2 which is the first moving lens unit,the aperture stop S, the third lens unit G3 which is the second movinglens unit, and the fourth lens unit G4.

The first lens unit G1 includes, in order from the object side, thenegative meniscus lens L1 ₁ with a convex surface directed toward theobject side, the reflective optical component R1 having a reflectingsurface for bending the optical path, and the biconvex positive lens L1₂, having positive refracting power as a whole.

The reflective optical component R1 is constructed as a reflecting prismbending the optical path by 90°.

The second lens unit G2 includes, in order from the object side, thecemented lens with the biconcave negative lens L2 ₁ and the positivemeniscus lens L2 ₂ with a convex surface directed toward the objectside, having negative refracting power as a whole.

The third lens unit G3 includes, in order from the object side, thebiconvex positive lens L3 ₁′ and the cemented lens with the positivemeniscus lens L3 ₂′ with a convex surface directed toward the objectside and the negative meniscus lens L3 ₃′ with a convex surface directedtoward the object side, having positive refracting power as a whole.

The fourth lens unit G4 includes the positive meniscus lens L4 ₁′″ witha convex surface directed toward the object side and a negative lens L4₂″ having a concave surface on the object side and a flat surface on theimage side.

When the magnification of the zoom lens is changed, extending from thewide-angle position to the telephoto position, in focusing of theinfinite object point, the first lens unit G1 and the fourth lens unitG4 remain fixed; the second lens unit G2 is moved back and forth on theimage side to follow a convex path (that is, after being moved towardthe image side to widen once spacing between the first lens unit G1 andthe second lens unit G2, narrows the spacing while moving toward theobject side); and the third lens unit G3 is moved toward the object sideonly, together with the aperture stop S.

In focusing of the short-distance object point, the second lens unit G2is shifted to the object side.

Also, when the first lens unit G1 and the fourth lens unit G4 remainfixed even when the focusing operation is performed.

Aspherical surfaces are provided to the image-side surface of thenegative meniscus lens L1 ₁ with a convex surface directed toward theobject side in the first lens unit G1, the object-side surface of thebiconvex positive lens L3 ₁′ in the third lens unit G3, and theobject-side surface of the positive meniscus lens L4 ₁′″ with a convexsurface directed toward the object side and the object-side surface ofthe negative lens L4 ₂″ having a concave surface on the object side anda flat surface on the image side in the fourth lens unit G4.

Subsequently, numerical data of optical members constituting the zoomlens of the sixteenth embodiment are shown below.

Numerical data 16 r₁ = 31.8167 d₁ = 0.9000 n_(d1) = 1.74320 ν_(d1) =49.34 r₂ = 6.5130 (aspherical) d₂ = 2.0500 r₃ = ∞ d₃ = 8.4000 n_(d3) =1.80610 ν_(d3) = 40.92 r₄ = ∞ d₄ = 0.1500 r₅ = 12.2002 d₅ = 1.7500n_(d5) = 1.72916 ν_(d5) = 54.68 r₆ = −176.2299 d₆ = D6 r₇ = −12.2304 d₇= 0.7000 n_(d7) = 1.72916 ν_(d7) = 54.68 r₈ = 11.5000 d₈ = 1.3500 n_(d8)= 1.84666 ν_(d8) = 23.78 r₉ = 32.1701 d₉ = D9 r₁₀ = ∞ (stop) d₁₀ = 0 r₁₁= 12.3535 (aspherical) d₁₁ = 1.7000 n_(d11) = 1.58313 ν_(d11) = 59.38r₁₂ = −9.7878 d₁₂ = 0.1500 r₁₃ = 4.1265 d₁₃ = 1.9500 n_(d13) = 1.69350ν_(d13) = 53.21 r₁₄ = 22.0000 d₁₄ = 0.7000 n_(d14) = 1.78470 ν_(d14) =26.29 r₁₅ = 2.9294 d₁₅ = D15 r₁₆ = 10.1130 (aspherical) d₁₆ = 1.4500n_(d16) = 1.58313 ν_(d16) = 59.38 r₁₇ = 2083.7929 d₁₇ = D17 r₁₈ =−216.5126 d₁₈ = 0.9000 n_(d18) = 1.52542 ν_(d18) = 55.78 (aspherical)r₁₉ = ∞ d₁₉ = 0.6000 r₂₀ = ∞ d₂₀ = 0.7500 n_(d20) = 1.51633 ν_(d20) =64.14 r₂₁ = ∞ d₂₁ = D21 r₂₂ = ∞ (imaging plane) d₂₂ = 0 Asphericalcoefficients Second surface K = 0 A₂ = 0 A₄ = −4.7792 × 10⁻⁴ A₆ = 8.5290× 10⁻⁶ A₈ = −4.3636 × 10⁻⁷ A₁₀ = 0 Eleventh surface K = 0 A₂ = 0 A₄ =−5.7279 × 10⁻⁴ A₆ = 5.4469 × 10⁻⁶ A₈ = −3.8768 × 10⁻⁷ A₁₀ = 0 Sixteenthsurface K = 0 A₂ = 0 A₄ = −4.2891 × 10⁻⁵ A₆ = 9.1978 × 10⁻⁵ A₈ = −1.0100× 10⁻⁵ A₁₀ = 0 Eighteenth K = 0 A₂ = 0 A₄ = −1.1036 × 10⁻³ A₆ = 2.0641 ×10⁻⁵ A₈ = 9.2983 × 10⁻⁶ A₁₀ = 0

Zoom data Wide-angle Middle Telephoto When the distance D0 is ∞, f(mm)4.00153 6.92963 12.00205 Fno 2.6604 3.4644 5.0148 D0 ∞ ∞ ∞ D6 1.100933.68362 1.10192 D9 10.12509 4.25142 0.60401 D15 3.24220 6.53134 12.76221D17 0.70000 0.70000 0.70000 D21 1.00000 1.00000 1.00000 When thedistance D0 is short (20 cm), D0 200.0000 200.0000 200.0000 D6 1.100933.68362 1.10192 D9 10.12509 4.25142 0.60401 D15 3.07343 6.04460 11.44083D17 0.86877 1.18674 2.02138 D21 1.00000 1.00000 1.00000

Subsequently, the values of parameters of the conditions in the eighthto sixteenth embodiments are listed in Tables 3-5.

TABLE 3 8th embodiment 9th embodiment 10th embodiment Lens dataNumerical data 8 Numerical data 9 Numerical data 10 Type of the thirdlens unit B B B Half field angle 32.6 32.5 32.4 at wide-angle positionHalf field angle 19.1 19.1 19.1 at middle position Half field angle 11.311.3 11.3 at telephoto position L 3.96 3.96 3.96 f11/{square root over((fw · fT))} −1.69849 −1.61753 −1.54777 f12/{square root over((fw · fT))} 2.68319 2.34639 2.09325 d/L 1.41793 1.41793 1.41793 npri1.80610 1.80610 1.80610 ν1N 40.92 40.92 34.97 {square root over((fw · fT))}/f1 −0.00099 0.07744 0.14219 βRW −0.55510 −0.60998 −0.60966fRW/{square root over ((fw · fT))} 1.39721 1.39226 1.39071 D12min/{square root over ((fw · fT))} — 0.19368 0.19335 fF/{square rootover ((fw · fT))} −3.23206 — — R_(C3)/R_(C1) 0.95846 0.97079 1.01613L/R_(C2) 0.19800 0.20842 0.20842 ν_(CP) − ν_(CN) 25.56 25.56 29.43(R_(1PF) + R_(1PR))/(R_(1PF) − R_(1PR)) −0.96138 −0.48393 −0.64140(R_(2F) + R_(2R))/(R_(2F) − R_(2R)) −0.51063 −0.40838 −0.30835 fT/fw2.99856 2.98732 2.97829 τ600/τ550 1.0 1.0 1.0 τ700/τ550 0.04 0.04 0.04τ400/τ550 0.0 0.0 0.0 τ440/τ550 1.06 1.06 1.06

TABLE 4 11th embodiment 12th embodiment 13th embodiment Lens dataNumerical data 11 Numerical data 12 Numerical data 13 Type of the thirdlens unit B B A Half field angle 32.6 32.3 33.4 at wide-angle positionHalf field angle 19.1 19.1 19.3 at middle position Half field angle 11.311.3 11.6 at telephoto position L 3.96 3.96 5.0 f11/{square root over((fw · fT))} −1.53510 −1.45358 −1.67788 f12/{square root over((fw · fT))} 2.16588 1.80986 2.32249 d/L 1.41793 1.41793 1.35018 npri1.80610 1.80610 1.80610 ν1N 40.92 34.97 49.34 {square root over((fw · fT))}/f1 0.12196 0.28698 0.07654 βRW −0.55821 −0.60428 −0.47307fRW/{square root over ((fw · fT))} 1.40791 1.39707 1.21583 D12min/{square root over ((fw · fT))} 0.19413 0.19169 0.19318 fF/{squareroot over ((fw · fT))} — — — R_(C3)/R_(C1) 0.93476 0.97454 0.66002L/R_(C2) 0.23294 0.35689 0.12500 ν_(CP) − ν_(CN) 25.56 29.43 26.92(R_(1PF) + R_(1PR))/(R_(1PF) − R_(1PR)) −0.39132 +0.09571 −1.20092(R_(2F) + R_(2R))/(R_(2F) − R_(2R)) −0.32313 −0.04010 −0.46272 fT/fw2.99207 2.95207 2.99456 τ600/τ550 1.0 1.0 1.0 τ700/τ550 0.04 0.04 0.04τ400/τ550 0.0 0.0 0.0 τ440/τ550 1.06 1.06 1.06

TABLE 5 14th embodiment 15th embodiment 16th embodiment Lens dataNumerical data 14 Numerical data 15 Numerical data 16 Type of the thirdlens unit A A A Half field angle 33.3 33.3 33.5 at wide-angle positionHalf field angle 19.3 19.4 19.5 at middle position Half field angle 11.611.6 11.6 at telephoto position L 5.0 5.0 5.0 f11/{square root over((fw · fT))} −1.74801 −1.66671 −1.61450 f12/{square root over((fw · fT))} 2.47933 2.24917 2.26694 d/L 1.34018 1.35018 1.37018 npri1.80610 1.80610 1.80610 ν1N 49.34 49.34 49.34 {square root over((fw · fT))}/f1 0.04585 0.09703 0.089115 βRW −0.48124 −0.47213 −0.43431fRW/{square root over ((fw · fT))} 1.22063 1.21369 1.11568 D12min/{square root over ((fw · fT))} 0.19150 0.19362 — fF/{square rootover ((fw · fT))} — — 2.51407 R_(C3)/R_(C1) 0.69594 0.65438 0.70990L/R_(C2) 0.50000 0.12500 0.22727 ν_(CP) − ν_(CN) 25.56 26.92 26.92(R_(1PF) + R_(1PR))/(R_(1PF) − R_(1PR)) −1.31703 −1.15556 −0.87051(R_(2F) + R_(2R))/(R_(2F) − R_(2R)) −0.79435 −0.44013 −0.44909 fT/fw2.99746 2.99478 2.99937 τ600/τ550 1.0 1.0 1.0 τ700/τ550 0.04 0.04 0.04τ400/τ550 0.0 0.0 0.0 τ440/τ550 1.06 1.06 1.06

In any of the embodiments of the present invention, the direction inwhich the optical path is bent is set in the direction of the major side(horizontal direction) of the electronic image sensor (CCD) as mentionedabove. Since the optical path can also be bent in a vertical direction,a minimum space is required for bending, which is advantageous forcompactness. If the optical path can also be bent in the direction ofthe minor side thereof, it will be bent in the direction of either themajor or minor side, and the number of degrees of design freedom of acamera incorporating lenses will be increased, which is favorable.

Also, although in each embodiment a low-pass filter is not incorporated,it may be introduced into the optical path. In the horizontal pixelpitch a of the electronic image sensor, any of the values given in Table6 may be used.

TABLE 6 a (μm) 4.0 3.7 3.4 3.1 2.8 2.6 2.4 2.2 2.0 1.8

In Tables 1 and 2, the bending point stands for a distance (of a 45°reflecting surface on the optical axis) from the front of the virtualplane (the third surface) of the lens data.

Also, in each embodiment, the reflecting surface in the numerical databecomes flat in focusing of the infinite object point and concave infocusing of the short-distance object point.

In view of the principle of a variable profile, it is desirable thateven in focusing of the infinite object point, the reflecting surface isconstructed to be somewhat concave, and in focusing of theshort-distance object point, it is constructed as a concave surfacewhich is stronger in curvature. The radius of curvature of thereflecting surface is measured at the point of intersection with theoptical axis, and the reflecting surface may be aspherical.

Here, reference is made to the diagonal length L of the effectiveimaging area and the pixel pitch a of the electronic image sensor. FIG.78 shows an example of a pixel array of the electronic image sensor usedin each embodiment of the present invention. At the pixel pitch a,pixels for R (red), G (green), and B (blue) or four-color pixels (FIG.81) for cyan, magenta, yellow, and green are arrayed in a mosaicfashion. The effective imaging area refers to the area of aphotoelectric conversion plane on the image sensor used for reproduction(display on the personal computer or printing by the printer) of aphotographed image. The effective imaging area depicted in the figure isset in the area narrower than the entire photoelectric conversion planeof the image sensor to the performance of the optical system (an imagecircle that the performance of the optical system can be ensured). Thediagonal length L of the effective imaging area is that of thiseffective imaging area. Also, the imaging area used for the reproductionof the image may be variously changed, but when the zoom lens of thepresent invention is used in an imaging device of such a function, thediagonal length L of the effective imaging area is changed. In such acase, the diagonal length L of the effective imaging area in the presentinvention is assumed to be the maximum value in a possible area.

In each embodiment mentioned above, a near-infrared cutoff filter isplaced on the image side of the last lens unit, or a near-infraredcutoff coat is applied to the surface of the entrance-side of the CCDcover glass CG or another lens. The low-pass filter is not placed in theoptical path from the entrance surface of the zoom lens to the imagingplane. The near-infrared cutoff filter or the near-infrared cutoff coatis designed so that the transmittance at a wavelength of 60 nm is morethan 80% and the transmittance at a wavelength of 700 nm is less than10%. Specifically, it has a multilayer film composed of 27 layers suchas are described below. However, its design wavelength is 780 nm.

Substrate Material Physical film thickness (nm) λ/4 1st layer Al₂O₃58.96 0.50 2nd layer TiO₂ 84.19 1.00 3rd layer SiO₂ 134.14 1.00 4thlayer TiO₂ 84.19 1.00 5th layer SiO₂ 134.14 1.00 6th layer TiO₂ 84.191.00 7th layer SiO₂ 134.14 1.00 8th layer TiO₂ 84.19 1.00 9th layer SiO₂134.14 1.00 10th layer TiO₂ 84.19 1.00 11th layer SiO₂ 134.14 1.00 12thlayer TiO₂ 84.19 1.00 13th layer SiO₂ 134.14 1.00 14th layer TiO₂ 84.191.00 15th layer SiO₂ 178.41 1.33 16th layer TiO₂ 101.03 1.21 17th layerSiO₂ 167.67 1.25 18th layer TiO₂ 96.82 1.15 19th layer SiO₂ 147.55 1.0520th layer TiO₂ 84.19 1.00 21st layer SiO₂ 160.97 1.20 22nd layer TiO₂84.19 1.00 23rd layer SiO₂ 154.26 1.15 24th layer TiO₂ 95.13 1.13 25thlayer SiO₂ 160.97 1.20 26th layer TiO₂ 99.34 1.18 27th layer SiO₂ 87.190.65 Air

The transmittance characteristics of the near-infrared sharp cutoff coatare as shown in FIG. 79. A color filter reducing the transmission ofcolor in the short-wavelength region such as that shown in FIG. 80 isprovided on the side of the entrance surface of the CCD cover glass CGto which the near-infrared cutoff coat is applied or another lens towhich the near-infrared cutoff coat is applied, or a coating is providedto the entrance surface. Whereby, color reproducibility of an electronicimage is further improved.

Specifically, it is favorable that, owing to the near-infrared cutofffilter or the near-infrared cutoff coating, the ratio of thetransmittance between the wavelength of the highest transmittance ofwavelengths of 400-700 nm and a wavelength of 420 nm is more than 15%and the ratio of the transmittance between the wavelength of the highesttransmittance and a wavelength of 400 nm is less than 6%.

Whereby, a shift between the recognition of the human eye to color andthe color of an image produced and reproduced can be reduced. In otherwords, color on the short-wavelength side which is hard to be recognizedwith the human vision is easily recognized with the human eye, and thedegradation of an image due thereto can be prevented. If the ratio ofthe transmittance of the wavelength of 400 nm exceeds 6%, shortwavelengths which are hard to be recognized with the human eye will bereproduced to wavelengths which can be recognized. Conversely, if theratio of the transmittance of the wavelength of 420 nm is below 15%, thereproduction of wavelengths which can be recognized with the human eyebecomes difficult and a color balance will be impaired.

A means for limiting such wavelengths brings about an effect by using acomplementary mosaic color filter in the imaging system.

In each embodiment mentioned above, as shown in FIG. 80, the coating ismade so that the transmittance is 0% at a wavelength of 400 nm and 90%at a wavelength of 420 nm, and the peak of the transmittance is 100% ata wavelength of 440 nm.

By adding the function of the near-infrared sharp cutoff coat, the colorfilter is such that, with a transmittance of 99% as a peak, thetransmittance is 0% at a wavelength of 400 nm, 80% at a wavelength of420 nm, 82% at a wavelength of 600 nm, and 2% at a wavelength of 700 nm.Whereby, more true color reproduction is made.

On the imaging plane I of the CCD, as illustrated in FIG. 81, isprovided the complementary mosaic color filter in which four-colorfilter components of cyan, magenta, yellow, and green are arrayed in amosaic fashion, corresponding to imaging pixels. These four-color filtercomponents are arrayed in the mosaic fashion so that the number ofindividual color filter components is almost the same and adjacentpixels do not correspond to the same kind of color filter components.Whereby, more true color reproduction becomes possible.

Specifically, as shown in FIG. 81, it is desirable that thecomplementary mosaic color filter is constructed with at least fourkinds of color filter components and the characteristics of the colorfilter components are as described below.

A color filter component G of green has the peak of a spectral intensityat a wavelength G_(P), a color filter component Y_(e) of yellow has thepeak of the spectral intensity at a wavelength Y_(P), a color filtercomponent C of cyan has the peak of the spectral intensity at awavelength C_(P), and a color filter component M of magenta has peaks atwavelengths M_(P1) and M_(P2), satisfying the following conditions:510 nm<G_(P)<540 nm5 nm<Y _(P) −G _(P)<35 nm−100 nm<C _(P) −G _(P)<−5 nm450 nm<M_(P1)<480 nm580 nm<M_(P2)<640 nm

Furthermore, it is favorable for the improvement of colorreproducibility that each of the color filter components of green,yellow, and cyan has a spectral intensity of at least 80% at awavelength of 530 nm with respect to the peak of the spectral intensity,and the color filter component of magenta has a spectral intensity of10-50% at a wavelength of 530 nm with respect to the peak of thespectral intensity.

An example of the wavelength characteristics of the color filtercomponents in the above embodiments is shown in FIG. 82. The colorfilter component G of green has the peak of the spectral intensity at awavelength of 525 nm. The color filter component Y_(e) of yellow has thepeak of the spectral intensity at a wavelength of 555 nm. The colorfilter component C of cyan has the peak of the spectral intensity at awavelength of 510 nm. The color filter component M of magenta has thepeaks at wavelengths of 440 nm and 620 nm. The spectral intensities ofthe color filter components at a wavelength of 530 nm are 90% for G, 95%for Y_(e), 97% for C, and 38% for M with respect to the peaks of thespectral intensities.

In such a complementary mosaic color filter, colors of the color filtercomponents are electrically converted into signals for R (red), G(green), and B (blue) by a controller, not shown, (or a controller usedin a digital camera), through the following signal processing:

luminance signalY=|G+M+Y _(e) +C|×¼

color signalsR−Y=|(M+Y _(e))−(G+C)|B−Y=|(M+C)−(G+Y _(e))|

Also, the near-infrared sharp cutoff coat may be located in any positionon the optical path.

In the numerical data of each embodiment, the description that thespacing between the aperture stop S and the convex surface of the nextlens on the image side is zero means that the position of the vertex ofthe convex surface of the lens is equal to the point of intersection ofa perpendicular line drawn to the optical axis from the aperture stopwith the optical axis.

Also, although the stop S is constructed as a flat plate in eachembodiment, a black painting member with a circular aperture may be usedas another structure. Alternatively, a funnel-shaped stop, such as thatshown in FIG. 83, may be covered along the inclination of the convexsurface of the lens. A stop may also be provided to a frame supporting alens.

Each embodiment described above is designed so that the variabletransmittance means for adjusting the amount of light in the presentinvention or a shutter for adjusting light-receiving time can be placedin air spacing on the image side of the third lens unit G3.

The light-amount adjusting means, as shown in FIG. 84, can be used as aturret-like structure in which a transparent window or a hollowaperture, an ND filter of ½ transmittance, an ND filter of ¼transmittance, and others are provided.

Its specific example is shown in FIG. 85. In this figure, however, thefirst and second lens units G1 and G2 are omitted for the sake ofconvenience. A turret 10, shown in FIG. 84, capable of adjustingbrightness at a zero stage, a -first stage, a -second stage, and a-third stage is located on the optical axis between the third and fourthlens units G3 and G4. The turret 10 is provided with aperture sections1A, 1B, 1C, and 1D having an ND filter of 100% transmittance, an NDfilter of 50% transmittance, an ND filter of 25% transmittance, and anND filter of 12.5% transmittance, respectively, with respect to thetransmittance at a wavelength 550 nm in an area transmitting aneffective light beam.

The turret 10 is rotated around a rotary axis 11 and any aperturesection is located on the optical axis between the lens units which isspacing different from the position of the stop. Whereby, thelight-amount adjustment is made.

For the light-amount adjusting means, as shown in FIG. 86, a filtersurface in which the light-amount adjustment is possible may be providedso that variation in the amount of light is suppressed. The filtersurface of FIG. 86 is constructed so that the transmittance isconcentrically different and the amount of light decreases progressivelyin going to the center.

The filter surface may be placed and constructed so that the amount oflight at the center is ensured in preference to others with respect to adark object to uniform the transmittance, and variation in brightness iscompensated with respect to a bright object alone.

In view of the slim design of the entire device, an electroopticalelement which is capable of electrically controlling the transmittancecan be used.

The electrooptical element, for example, as illustrated in FIG. 87, canbe constructed with a liquid crystal filter in which a TN liquid crystalcell is sandwiched between two transparent electrodes, each having apolarization film which coincides in polarization direction with thetransparent electrode, and voltages applied to the transparentelectrodes are properly changed to thereby vary the polarizationdirection in the liquid crystal and adjust the amount of transmissionlight.

In this liquid crystal filter, the voltage applied to the TN liquidcrystal cell is adjusted through a variable resistor, and thereby theorientation of the TN liquid crystal cell is changed.

Instead of various filters adjusting the transmittance, such as thosedescribed above, the shutter adjusting the light-receiving time may beprovided as the light-amount adjusting means. Alternatively, the shuttermay be placed together with the filters.

The shutter may be constructed as a focal-plane shutter with movingblades situated close to the image plane, or a two-blade lens shutter, afocal-plane shutter, or a liquid crystal shutter, provided on theoptical path.

FIGS. 88A and 88B show an example of a rotary focal-plane shutter whichis one focal-plane shutter adjusting the light-receiving time,applicable to the electronic imaging device of each embodiment in thepresent invention. FIGS. 89A-89D show states where a rotary shutterblade is turned.

In FIGS. 88A and 88B, reference symbol A represents a shutter baseplate, B represents a rotary shutter blade, C represents a rotary shaftof the rotary shutter blade, and D1 and D2 represent gears.

The shutter base plate A is constructed so that it is placed immediatelybefore the image plane, or on an arbitrary optical path, in theelectronic imaging device of the present invention. The shutter baseplate A is provided with an aperture A1 transmitting the effective lightbeam of the optical system. The rotary shutter blade B is configuredinto a semicircular shape. The rotary shaft C of the rotary shutterblade B is constructed integral with the rotary shutter blade B. Therotary shaft C is turned in regard of the shutter base plate A. Therotary shaft C is connected to the gears D1 and D2 provided on the rightside of the shutter base plate A. The gears D1 and D2 are connected to amotor, not shown.

By the drive of the motor, not shown, the rotary shutter blade B isturned sequentially in the order of FIGS. 89A-89D, with the rotary shaftC as a center, through the gears D1 and D2 and the rotary shaft C.

The rotary shutter blade B is turned to thereby close and open theaperture A1 of the shutter base plate A, and plays the role of theshutter.

A shutter speed is adjusted by changing the turning speed of the rotaryshutter blade B.

In the disclosure so far, reference has been made to the light-amountadjusting means. Such a shutter or variable transmittance filter isplaced in each embodiment of the present invention, for example, at thesixteenth surface of each of the first and the eighth to fifteenthembodiments. The light-amount adjusting means may be located at anotherposition if it is located at a position different from that of theaperture stop.

The electrooptical element may also be used as the shutter. This is morefavorable for a reduction in the number of parts and compactness of theoptical system.

Subsequently, a description is given of an example of a variable mirrorapplicable as a reflective optical component having the reflectingsurface for bending the optical path in the zoom lens of the presentinvention.

FIG. 90 shows one example of a deformable mirror 409 applicable as thereflective optical component having the reflecting surface for bendingthe optical path of the zoom lens of the present invention.

First, the basic construction of the deformable mirror 409 will bedescribed.

The deformable mirror 409 refers to a variable optical-propertydeformable mirror (which is hereinafter simply called a deformablemirror) having a thin film (reflecting surface) 409 of an aluminumcoating and a plurality of electrodes 409 b. Reference numeral 411denotes a plurality of variable resistors connected to the electrodes409 b, 414 denotes an arithmetical unit for controlling the resistancevalues of the plurality of variable resistors 411, and 415, 416, and 417denote a temperature sensor, a humidity sensor, and a range sensor,respectively, connected to the arithmetical unit 414. These are arrangedas shown in the figure to constitute one optical apparatus.

The deformable mirror need not necessarily be planar, and may have anyshape such as a spherical or rotationally symmetrical asphericalsurface; a spherical, planar, or rotationally symmetrical asphericalsurface which has decentration with respect to the optical axis; anaspherical surface with symmetrical surfaces; an aspherical surface withonly one symmetrical surface; an aspherical surface with no symmetricalsurface; a free-formed surface; a surface with a nondifferentiable pointor line; etc. Moreover, any surface which has some effect on light, suchas a reflecting or refracting surface, is satisfactory. In general, sucha surface is hereinafter referred as to an extended surface.

It is favorable that the profile of the reflecting surface of thedeformable mirror is a free-formed surface. This is because correctionfor aberration can be facilitated, which is advantageous.

The free-formed surface used in the present invention is defined by thefollowing equation. The Z axis in this defining equation constitutes anaxis of the free-formed surface.

$\begin{matrix}{Z = {{{cr}^{2}/\left\lbrack {1 + \sqrt{\left\{ {1 - {\left( {1 + k} \right)c^{2}r^{2}}} \right\}}} \right\rbrack} + {\sum\limits_{j = 2}^{M}{C_{j}X^{m}Y^{n}}}}} & (a)\end{matrix}$where, the first term of this equation is a spherical surface term, andthe second term is a free-formed surface term. M is a natural number of2 or larger.

In the spherical surface term,

-   c: curvature of the vertex,-   k: conic constant,-   r=√{square root over ((X²+Y²))}

The free-formed surface term is as follows:

${\sum\limits_{j = 2}^{M}{C_{j}X^{m}Y^{n}}} = {{C_{2}X} + {C_{3}Y} + {C_{4}X^{2}} + {C_{5}X\; Y} + {C_{6}Y^{2}} + {C_{7}X^{3}} + {C_{8}X^{2}Y} + {C_{9}X\; Y^{2}} + {C_{10}Y^{3}} + {C_{11}X^{4}} + {C_{12}X^{3}Y} + {C_{13}X^{2}Y^{2}} + {C_{14}X\; Y^{3}} + {C_{15}Y^{4}} + {C_{16}X^{5}} + {C_{17}X^{4}Y} + {C_{18}X^{3}Y^{2}} + {C_{19}X^{2}Y^{3}} + {C_{20}X\; Y^{4}} + {C_{21}Y^{5}} + {C_{22}X^{6}} + {C_{23}X^{5}Y} + {C_{24}X^{4}Y^{2}} + {C_{25}X^{3}Y^{3}} + {C_{26}C^{2}Y^{4}} + {C_{27}X\; Y^{5}} + {C_{28}Y^{6}} + {C_{29}X^{7}} + {C_{30}X^{6}Y} + {C_{31}X^{5}Y^{2}} + {C_{32}X^{4}Y^{3}} + {C_{33}X^{3}Y^{4}} + {C_{34}X^{2}Y^{5}} + {C_{35}X\; Y^{6}} + {C_{36}Y^{7}\mspace{11mu}\ldots}}$where, C_(j) (j is an integer of 2 or larger) is a coefficient.

The above-mentioned free-formed surface never generally has a symmetricsurface for both the X-Z plane and the Y-Z plane. However, by bringingall odd-number order terms of X to 0, a free-formed surface having onlyone symmetrical surface parallel to the Y-Z plane is obtained. Bybringing all odd-number order terms of Y to 0, a free-formed surfacehaving only one symmetrical surface parallel to the X-Z plane isobtained.

In the deformable mirror of this example, as shown in FIG. 90, apiezoelectric element 409 c is interposed between the thin film 409 aand the plurality of electrodes 409 b, and these are placed on thesupport 423. A voltage applied to the piezoelectric element 409 c ischanged in accordance with each of the electrodes 409 b, and thereby thepiezoelectric element 409 c causes expansion and contraction which arepartially different so that the shape of the thin film 409 a can bechanged. The configuration of the electrodes 409 b, as illustrated inFIG. 91, may have a concentric division pattern, or as in FIG. 92, maybe a rectangular division pattern. As other patterns, properconfigurations can be chosen. In FIG. 90, reference numeral 424represents a shake sensor connected to the arithmetical unit 414. Theshake sensor 424, for example, detects the shake of a digital camera andchanges the voltages applied to the electrodes 409 b through thearithmetical unit 414 and variable resistors 411 in order to deform thethin film 409 a to compensate for the blurring of an image caused by theshake. At this time, signals from the temperature sensor 415, thehumidity sensor 416, and range sensor 417 are taken into accountsimultaneously, and focusing and compensation for temperature andhumidity are performed. In this case, stress is applied to the thin film409 a by the deformation of the piezoelectric element 409 c, and henceit is good practice to design the thin film 409 a so that it has amoderate thickness and a proper strength.

FIG. 93 shows another example of the deformable mirror 409 applicable asthe reflective optical component having the reflecting surface forbending the optical path of the zoom lens of the present invention. Thedeformable mirror of this example has the same construction as thedeformable mirror of FIG. 90 with the exception that two piezoelectricelements 409 c and 409 c′ are interposed between the thin film 409 a andthe plurality of electrodes 409 b and are made with substances havingpiezoelectric characteristics which are reversed in direction.Specifically, when the piezoelectric elements 409 c and 409 c′ are madewith ferroelectric crystals, they are arranged so that their crystalaxes are reversed in direction with respect to each other. In this case,the piezoelectric elements 409 c and 409 c′ expand or contract in areverse direction when voltages are applied, and thus there is theadvantage that a force for deforming the thin film (reflecting surface)409 a becomes stronger than in the example of FIG. 90, and as a result,the shape of the mirror surface can be considerably changed.

For substances used for the piezoelectric elements 409 c and 409 c′, forexample, there are piezoelectric substances such as barium titanate,Rochelle salt, quartz crystal, tourmaline, KDP, ADP, and lithiumniobate; polycrystals or crystals of the piezoelectric substances;piezoelectric ceramics such as solid solutions of PbZrO₃ and PbTiO₃;organic piezoelectric substances such as PVDF; and other ferroelectrics.In particular, the organic piezoelectric substance has a small value ofYoung's modulus and brings about a considerable deformation at a lowvoltage, which is favorable. When these piezoelectric elements are used,it is also possible to properly deform the thin film 409 a in each ofthe above examples if their thicknesses are made uneven.

As materials of the piezoelectric elements 409 c and 409 c′,high-polymer piezoelectrics such as polyurethane, silicon rubber,acrylic elastomer, PZT, PLZT, and PVDF; vinylidene cyanide copolymer;and copolymer of vinylidene fluoride and tri-fluoroethylene are used.

The use of an organic substance, synthetic resin, or elastomer, having apiezoelectric property, brings about a considerable deformation of thesurface of the deformable mirror, which is favorable.

When an electrostrictive substance, for example, acrylic elastomer orsilicon rubber, is used for the piezoelectric element 409 c shown inFIGS. 90 and 94, the piezoelectric element 409 c, as indicated by abroken line in FIG. 90, may have the two-layer structure in which asubstrate 409 c-1 is cemented to an electrostrictive substance 409 c-2.

FIG. 94 shows still another example of the deformable mirror 409applicable as the reflective optical component having the reflectingsurface for bending the optical path of the zoom lens of the presentinvention. The deformable mirror of this example is designed so that thepiezoelectric element 409 c is sandwiched between the thin film 409 aand a plurality of electrodes 409 d, and these are placed on the support423. Voltages are applied to the piezoelectric element 409 c between thethin film 409 a and the electrodes 409 d through a driving circuit 425 acontrolled by the arithmetical unit 414. Furthermore, apart from this,voltages are also applied to the plurality of electrodes 409 b providedon a bottom surface inside the support 423, through driving circuits 425b controlled by the arithmetical unit 414. Therefore, the thin film 409a can be doubly deformed by electrostatic forces due to the voltagesapplied between the thin film 409 a and the electrodes 409 d and appliedto the electrodes 409 b. There are advantages that various deformationpatterns can be provided and the response is quick, compared with any ofthe above examples.

By changing the signs of the voltages applied between the thin film 409a and the electrodes 409 d, the thin film 409 a of the deformable mirror409 can be deformed into either a convex or concave surface. In thiscase, a considerable deformation may be performed by a piezoelectriceffect, while a slight shape change may be carried out by theelectrostatic force. Alternatively, the piezoelectric effect may bechiefly used for the deformation of the convex surface, while theelectrostatic force may be used for the deformation of the concavesurface. Also, the electrodes 409 d may be constructed as a singleelectrode or a plurality of electrodes like the electrodes 409 b. Thecondition of electrodes 409 d constructed as the plurality of electrodesis shown in FIG. 94. In the description, all of the piezoelectriceffect, the electrostrictive effect, and electrostriction are generallycalled the piezoelectric effect. Thus, it is assumed that theelectrostrictive substance is included in the piezoelectric substance.

FIG. 95 shows another embodiment of the deformable mirror 409 applicableas the reflective optical component having the reflecting surface forbending the optical path of the zoom lens of the present invention. Thedeformable mirror 409 of this embodiment is designed so that the shapeof the reflecting surface can be changed by utilizing an electromagneticforce. A permanent magnet 426 is fixed on the bottom surface inside thesupport 423, and the periphery of a substrate 409 e made with siliconnitride or polyimide is mounted and fixed on the top surface thereof.The thin film 409 a with the coating of metal, such as aluminum, isdeposited on the surface of the substrate 409 e, thereby constitutingthe deformable mirror 409. Below the substrate 409 e, a plurality ofcoils 427 are fixedly mounted and connected to the arithmetical unit 414through driving circuits 428. In accordance with output signals from thearithmetical unit 414 corresponding to changes of the optical systemobtained at the arithmetical unit 414 by signals from the sensor 415,416, 417, and 424, proper electric currents are supplied from thedriving circuits 428 to the coils 427. At this time, the coils 427 arerepelled or attracted by the electromagnetic force with the permanentmagnet 426 to deform the substrate 409 e and the thin film 409 a.

In this case, a different amount of current can also be caused to flowthrough each of the coils 427. A single coil 427 may be used. Thepermanent magnet 426 may be mounted on the lower surface of thesubstrate 409 e so that the coils 427 are arranged on the bottom side inthe support 423. It is desirable that the coils 427 are constructed asthin film coils by a lithography process. A ferromagnetic iron core maybe encased in each of the coils 427.

In the thin film coils, each of the coils 427, as illustrated in FIG.96, can be designed so that a coil density varies with the place of thelower surface of the substrate 409 e, like a coil 428′, and thereby adesired deformation is brought to the substrate 409 e and the thin film409 a. A single coil 427 may be used, or a ferromagnetic iron core maybe encased in each of the coils 427.

FIG. 97 shows another example of the deformable mirror 409 applicable asthe reflective optical component having the reflecting surface forbending the optical path of the zoom lens of the present invention. Inthis figure, reference numeral 412 designates a power supply.

In the deformable mirror 409 of this example, the substrate 409 e ismade with a ferromagnetic such as iron, and the thin film 409 a as areflecting film is made with aluminum. The periphery of the substrate409 e is mounted and fixed on the top surface of the support 423. Thecoils 427 are fixed on the bottom side in the support 423. In this case,since the thin film coils need not be provided beneath the substrate 409e, the structure is simple and the manufacturing cost can be reduced. Ifthe power switch 413 is replaced with a changeover and power on-offswitch, the directions of currents flowing through the coils 427 can bechanged, and the configurations of the substrate 409 e and the thin film409 a can be changed at will. FIG. 98 shows an example of an array ofthe coils 427 arranged with respect to the thin film 409 a and thesubstrate 409 e. FIG. 99 shows another example of the array of the coils427. These arrays are also applicable to the example of FIG. 95. FIG.100 shows an array of the permanent magnets 426 suitable for the casewhere the coils 427, as shown in FIG. 99, are radially arrayed.Specifically, when the bar-shaped permanent magnets 426, as shown inFIG. 100, are radially arrayed, a delicate deformation can be providedto the substrate 409 e and the thin film 409 a in contrast with theexample of FIG. 95. As mentioned above, when the electromagnetic forceis used to deform the substrate 409 e and the thin film 409 a (in theexamples of FIGS. 95 and 97), there is the advantage that they can bedriven at a lower voltage than in the case where the electrostatic forceis used.

Some examples of the deformable mirrors have been described, but asshown in the example of FIG. 94, at least two kinds of forces may beused in order to change the shape of the mirror constructed with a thinfilm. Specifically, at least two of the electrostatic force,electromagnetic force, piezoelectric effect, magnetrostriction, pressureof a fluid, electric field, magnetic field, temperature change, andelectromagnetic wave, may be used simultaneously to deform thedeformable mirror. That is, when at least two different drivingtechniques are used to make the variable optical-property element, aconsiderable deformation and a slight deformation can be realizedsimultaneously and a mirror surface with a high degree of accuracy canbe obtained.

FIG. 101 shows an imaging system which uses the deformable mirror 409applicable as the reflective optical component having the reflectingsurface for bending the optical path of the zoom lens in another exampleof the present invention and is used, for example, in a digital cameraof a cellular phone, a capsule endoscope, an electronic endoscope, adigital camera for personal computers, or a digital camera for PDAs.

In the imaging optical system of this example, the reflective opticalcomponent R1 in the optical system shown in the first embodiment isconstructed as the deformable mirror 409. One imaging unit 104 isconstructed with the zoom lens, the CCD 408 which is the electronicimage sensor, and a control system 103. The imaging unit 104 of thisexample is designed so that light from an object passing through thenegative meniscus lens L1 ₁ with a convex surface directed toward theobject side is condensed by the deformable mirror 409 when reflected bythe thin film (reflecting surface) of the deformable mirror 409, and isimaged on the CCD 408 which is the solid-state image sensor, through thebiconvex positive lens L1 ₂, the second lens unit G2, the third lensunit G3, the fourth lens unit G4, and the CCD cover glass CG. Thedeformable mirror 409 is a kind of variable optical-property element andis also referred to as a variable focal-length mirror.

According to this example, even when the object distance is changed, thereflecting surface 409 a of the deformable mirror 409 is deformed andthereby the object can be brought into a focus. The example need notmove the lens 902 by using a motor and excels in compact and lightweightdesign and low power consumption. The imaging unit 104 can be used inany of the examples as the imaging optical system of the presentinvention. When a plurality of deformable mirrors 409 are used, anoptical system, such as a zoom imaging optical system or a variablemagnification imaging optical system, can be constructed.

In FIG. 32, an example of a control system is cited which includes theboosting circuit of a transformer using coils in the control system 103.When a laminated piezoelectric transformer is particularly used, acompact design is achieved. The boosting circuit can be used in thedeformable mirror of the present invention which uses electricity, andis useful in particular for the deformable mirror which utilizes theelectrostatic force or the piezoelectric effect. In order to use thedeformable mirror 409 for focusing, it is only necessary, for example,to form an object image on the solid-state image sensor 408 and to finda state where the high-frequency component of the object image ismaximized while changing the focal length of the deformable mirror 409.In order to detect the high-frequency component, it is only necessary,for example, to connect a processor including a microcomputer to thesolid-state image sensor 408 and to detect the high-frequency componenttherein.

The electronic imaging device using such a path bending zoom lens in thepresent invention can be used in the imaging device in which an objectimage is formed by the imaging optical system such as the zoom lens, andthis image is received by an image-forming element, such as the CCD or asilver halide film, to photograph, notably in a digital camera, a videocamera, a personal computer or a telephone which is an example of aninformation processor, or a cellular phone which is handy to carry. Itsembodiment is shown below.

FIGS. 102-104 show a digital camera in which the path bending zoom lensof the present invention is incorporated in an photographing opticalsystem 41. In the digital camera of FIG. 104, an imaging optical path isbent in a longitudinal direction of a finder, and an observer's eyeviewed from the upper side is shown.

A digital camera 40, in this example, includes the photographing opticalsystem 41 having a photographing optical path 42, a finder opticalsystem 43 having a finder optical path 44, a shutter 45, a flash lamp46, and a liquid crystal display monitor 47. When the shutter 45provided on the upper portion of the camera 40 is pushed, photographingis performed through the photographing optical system 41, for example,the path bending zoom lens of the first embodiment.

An object image formed by the photographing optical system 41 isprovided on the imaging plane of a CCD 49 through the near-infraredcutoff coat applied to the near-infrared cutoff filter, the CCD coverglass, or another lens.

The object image received by the CCD 49 is displayed on the liquidcrystal display monitor 47 provided on the back face of the camera as anelectronic image through a processing means 51. A recording means 52 isconnected to the processing means 51 and a photographed electronic imagecan be recorded. Also, the recording means 52 may be provided to beindependent of the processing means 51, or may be constructed so thatthe image is electronically recorded and written by a floppy (trademark)disk, memory card, or MO. A silver halide film camera using a silverhalide film instead of the CCD 49 may be employed.

A finder objective optical system 53 is located on the finder opticalpath 44. An object image formed by the finder objective optical system53 is provided on a field frame 57 of a Porro prism 55 which is an imageerecting member. Behind the Porro prism 55, an eyepiece optical system59 introducing an erect image into an observer's eye E is located. Also,cover members 50 are placed on the entrance side of the photographingoptical system 41 and the finder objective optical system 53 and on theexit side of the eyepiece optical system 59.

The digital camera 40 constructed as mentioned above has an effect on aslim design thereof by bending the optical path in the direction of themajor side. Since the photographing optical system 41 is a zoom lenswhich has a wide field angle and a high variable magnification ratio, isfavorable in aberration and bright, and is provided with a long backfocal distance that the filter can be placed, high performance and acost reduction can be realized.

Also, the photographing optical path of the digital camera 40 may bebent in the direction of the minor side of the finder. In this case, astroboscopic lamp (or the flash lamp) is placed in the upper directionof the entrance surface of a photographic lens to bring about the layoutthat the influence of shading caused in strobo-photography of a personcan be lessened.

In FIG. 104, plane-parallel plates are used as the cover members 50, butlenses with powers may be used.

Subsequently, a personal computer of an example of an informationprocessor in which the path bending zoom lens is incorporated as theobjective optical system is shown in FIGS. 105-107.

As shown in FIGS. 105-107, a personal computer 300 has a keyboard 301for inputting information from the exterior by an operator; aninformation processing means or recording means, not shown; a monitor302 displaying information for the operator, and an photographingoptical system 303 for photographing the operator himself or asurrounding image.

Here, the monitor 302 may be a transmission-type liquid crystal displayelement illuminated with backlight from the back face, a reflection-typeliquid crystal display element reflecting light from the front fordisplay, or a CRT display. In these figures, the photographing opticalsystem 303 is housed in the monitor 302 upper-right, but it may belocated, not to speak of this place, on the periphery of the monitor 302or the keyboard 301.

The photographing optical system 303 has an objective lens 112including, for example, the path bending zoom lens of the firstembodiment of the present invention and an imaging element chip 162receiving an image. These are housed in the personal computer 300.

Here, the cover glass CG is additionally cemented to the chip 162, andthese are integrally constructed as an imaging unit 160, which is fittedinto the rear end of a lens frame 113 of the objective lens 112 and canbe mounted in a single operation. Therefore, the alignment of theobjective lens 112 and the chip 162 and the adjustment of face-to-facespacing are not required, and assembly is simple. At the top (not shown)of the lens frame 113, a cover glass 114 for protecting the objectivelens 112 is placed. Also, the driving mechanism of the zoom lens in thelens frame 113 is not shown in the figure.

An object image received by the chip 162 is input into the processingmeans of the personal computer 300 through a terminal 166 and isdisplayed as an electronic image on the monitor 302. In FIG. 105, aphotographed image 305 of the operator is shown as an example. The image305 can also be displayed on the personal computer of his communicationmate from a remote place, by the processing means, through the internetor the telephone.

FIGS. 108A-108C show a telephone which is an example of the informationprocessor in which the path bending zoom lens of the present inventionis housed as the photographing optical system, notably a cellular phonewhich is handy to carry.

A cellular phone 400, as shown in FIGS. 108A-108C, includes a microphonesection 401 inputting an operator's voice as information; a speakersection 402 outputting the voice of a communication mate; input dials403 in which an operator inputs information; a monitor 404 displayinginformation, such as photographing images of the operator himself andthe communication mate, and telephone numbers; a photographing opticalsystem 405; an antenna 406 transmitting and receiving electric waves forcommunication; and a processing means (not shown) processing imageinformation, communication information, and an input signal. Here, themonitor 404 is a liquid crystal display element. In these figures, thearrangement of individual parts is not limited to the above description.The photographing optical system 405 has the objective lens 112including, for example, the path bending zoom lens of the firstembodiment in the present invention, located on a photographing opticalpath 407, and the chip 162 receiving the object image. These areincorporated in the cellular phone 400.

Here, the cover glass CG is additionally cemented to the chip 162, andthese are integrally constructed as the imaging unit 160, which isfitted into the rear end of the lens frame 113 of the objective lens 112and can be mounted in a single operation. Therefore, the alignment ofthe objective lens 112 and the chip 162 and the adjustment offace-to-face spacing are not required, and assembly is simple. At thetop (not shown) of the lens frame 113, the cover glass 114 forprotecting the objective lens 112 is placed. Also, the driving mechanismof the zoom lens in the lens frame 113 is not shown in the figure.

An object image received by the chip 162 is input into the processingmeans, not shown, through the terminal 166 and is displayed as theelectronic image on either the monitor 404 or the monitor of thecommunication mate, or both. Also, the processing means includes asignal processing function that when the image is transmitted to thecommunication mate, the information of the object image received by thechip 162 is converted into a transmittable signal.

1. An electronic imaging device comprising: a zoom lens; an electronicimage sensor located on an image side of the zoom lens; and a displaymonitor which displays an object image received by the electronic imagesensor, wherein the zoom lens comprises: a fixed lens unit remainingfixed on an optical axis when a magnification of the zoom lens ischanged and a focusing operation is performed; a first moving lens unitlying on an image side of the fixed lens unit, moved along the opticalaxis when the magnification is changed; and a second moving lens unitmoved along the optical axis when the magnification is changed; and anaperture stop that determines an F value at a wide-angle position of thezoom lens, wherein the fixed lens unit comprises a reflective opticalcomponent having a reflecting surface for reflecting an optical path,and wherein the electronic imaging device satisfies the followingconditions:1.8<fT/fwF≧a/(1 μm) where fw is a focal length of an entire system at thewide-angle position of the zoom lens, fT is a focal length of the entiresystem at a telephoto position of the zoom lens, a is a horizontal pixelpitch of the electronic image sensor, and F is an open F value at thewide-angle position of the zoom lens.
 2. The electronic imaging deviceaccording to claim 1, wherein a total number of reflecting surfaces inthe reflective optical component is one.
 3. The electronic imagingdevice according to claim 1, wherein a total number of reflectingsurfaces in the zoom lens is one.
 4. The electronic imaging deviceaccording to claim 1, wherein the second moving lens unit is laid on animage side of the first moving lens unit.
 5. The electronic imagingdevice according to claim 4, wherein a space on the optical path betweenthe first moving lens unit and the second moving lens unit is free fromanother lens unit.
 6. The electronic imaging device according to claim4, wherein the zoom lens further comprises a most image-side lens unitlocated at a most image-side position in the zoom lens, wherein thefirst moving lens unit has negative refracting power, and wherein thesecond moving lens unit has positive refracting power.
 7. The electronicimaging device according to claim 6, wherein the most image-side lensunit is fixed on the optical axis when a focusing operation isperformed.
 8. The electronic imaging device according to claim 6,wherein the most image-side lens unit is fixed on the optical axis whenthe magnification is changed.
 9. The electronic imaging device accordingto claim 4, wherein the zoom lens further comprises: a most image-sidelens unit located at a most image-side position in the zoom lens; and alens unit interposed between the second moving lens unit and the mostimage-side lens unit and moved along the optical axis in focusing onto ashorter-distance object point.
 10. The electronic imaging deviceaccording to claim 4, wherein the second moving lens unit comprises, inorder from an object side, a single lens and a cemented lens component,and wherein a total number of lens elements included in the secondmoving lens unit is three.
 11. The electronic imaging device accordingto claim 4, wherein the second moving lens unit comprises, in order froman object side, a cemented lens component and a single lens, and whereina total number of lens elements included in the second moving lens unitis three.
 12. The electronic imaging device according to claim 4,wherein the second moving lens unit comprises a cemented triplet lenscomponent.
 13. The electronic imaging device according to claim 1,wherein the fixed lens unit is located at a most object-side position.14. The electronic imaging device according to claim 1, wherein thefixed lens unit comprises, in order from an object side, a negative lenscomponent, the reflective optical component, and a positive lenscomponent.
 15. The electronic imaging device according to claim 1,wherein the first moving lens unit is shifted to an object side infocusing onto a shorter-distance object point.
 16. The electronicimaging device according to claim 1, wherein the first moving lens unitcomprises, in order from an object side, a negative lens element and apositive lens element.
 17. The electronic imaging device according toclaim 1, wherein the horizontal pixel pitch of the electronic imagesensor is 2.8μm or less.
 18. The electronic imaging device according toclaim 1, wherein the horizontal pixel pitch of the electronic imagesensor is 2.6μm or less.
 19. The electronic imaging device according toclaim 1, wherein the horizontal pixel pitch of the electronic imagesensor is 2.0μm or less.
 20. The electronic imaging device according toclaim 1, wherein the reflective optical component is a prism andsatisfies the following condition:1.55<npri where npri is a refractive index, for d-line rays, of a mediumof which the reflective optical component is made.
 21. An electronicimaging device comprising: a zoom lens; an electronic image sensorlocated on an image side of the zoom lens; and a display monitor whichdisplays an object image received by the electronic image sensor,wherein the zoom lens comprises: a fixed lens unit remaining fixed on anoptical axis when a magnification of the zoom lens is changed and afocusing operation is performed; a first moving lens unit lying on animage side of the fixed lens unit, moved along the optical axis when themagnification is changed; and a second moving lens unit lying on animage side of the first moving lens unit, moved along the optical axiswhen the magnification is changed, wherein the fixed lens unit comprisesa reflective optical component having a reflecting surface forreflecting an optical path, wherein a total number of reflectingsurfaces in the fixed lens unit is one, wherein the first moving lensunit has negative refracting power, wherein the first moving lens unitis moved back and forth along the optical axis to follow a path convextoward an image side when the magnification is changed from a wide-angleposition to a telephoto position, and wherein the second moving lensunit has positive refracting power.
 22. The electronic imaging deviceaccording to claim 21, wherein a total number of reflecting surfaces inthe zoom lens is one.
 23. The electronic imaging device according toclaim 21, wherein the fixed lens unit is located at a most object-sideposition.
 24. The electronic imaging device according to claim 21,wherein the fixed lens unit comprises, in order from an object side, anegative lens component, the reflective optical component, and apositive lens component.
 25. The electronic imaging device according toclaim 21, wherein a space on the optical path between the first movinglens unit and the second moving lens unit is free from another lensunit.
 26. The electronic imaging device according to claim 21, whereinthe zoom lens further comprises a most image-side lens unit located at amost image-side position in the zoom lens, wherein the first moving lensunit has negative refracting power, and wherein the second moving lensunit has positive refracting power.
 27. The electronic imaging deviceaccording to claim 26, wherein the most image-side lens unit is fixed onthe optical axis when a focusing operation is performed.
 28. Theelectronic imaging device according to claim 26, wherein the mostimage-side lens unit is fixed on the optical axis when the magnificationis changed.
 29. The electronic imaging device according to claim 21,wherein the first moving lens unit is shifted to an object side infocusing onto a shorter-distance object point.
 30. The electronicimaging device according to claim 21, wherein the zoom lens furthercomprises: a most image-side lens unit located at a most image-sideposition in the zoom lens; and a lens unit interposed between the secondmoving lens unit and the most image-side lens unit and moved along theoptical axis in focusing onto a shorter-distance object point.
 31. Theelectronic imaging device according to claim 21, wherein the secondmoving lens unit comprises, in order from an object side, a single lensand a cemented lens component, and wherein a total number of lenselements included in the second moving lens unit is three.
 32. Theelectronic imaging device according to claim 21, wherein the secondmoving lens unit comprises, in order from an object side, a cementedlens component and a single lens, and wherein a total number of lenselements included in the second moving lens unit is three.
 33. Theelectronic imaging device according to claim 21, wherein the secondmoving lens unit comprises a cemented triplet lens component.
 34. Theelectronic imaging device according to claim 21, wherein the firstmoving lens unit comprises, in order from an object side, a negativelens element and a positive lens element.
 35. The electronic imagingdevice according to claim 21, wherein the horizontal pixel pitch of theelectronic image sensor is 2.8μm or less.
 36. The electronic imagingdevice according to claim 21, wherein the horizontal pixel pitch of theelectronic image sensor is 2.6μm or less.
 37. The electronic imagingdevice according to claim 21, wherein the horizontal pixel pitch of theelectronic image sensor is 2.0μm or less.
 38. The electronic imagingdevice according to claim 21, wherein the reflective optical componentis a prism and satisfies the following condition:1.55<npri where npri is a refractive index, for d-line rays, of a mediumof which the reflective optical component is made.